Unless you've bought a new PC in the past two years, there's a good chance that you're still running Windows XP - plenty of users are. Microsoft would obviously like you to upgrade to Windows 7, however, and now could be a wise time to make the switch.

Unfortunately, while an upgrade over the existing Windows installation is relatively simple to do from within Vista, the software giant hasn't made it easy to upgrade to Windows 7 from XP. Never fear: we'll walk you through the process.

Microsoft's advice is to transfer your personal files and folders to an external storage device, install a clean version of Windows 7 on your PC's hard drive, then reinstall all your files and programs. You can do this manually or with the so-called Windows Easy Transfer program. But, even if you can get this to work, it'll merely help transfer your files to an external hard drive. You'll still need to manually reinstall all your programs, enter their serial codes and configure them.

There are alternatives to all this hard work. For example, there are utilities that promise to help synchronise data between PCs - in this case, between your machine with XP on board, and the same PC after Windows 7 has been installed. Alternatively, you could install Windows 7 and boot XP in a virtual environment. With both OSes running at the same time, you can easily return to your 'old' PC at any time and transfer files and settings at your leisure.

With all the work required to make the move to Windows 7, you may instead be considering buying a new computer. But plenty of readers have decided that this new PC need not necessarily be a Windows one: both the Linux and Mac platforms are growing in popularity.

Now that Apple has transitioned all its Mac hardware to use Intel processors, it's quite easy to run Windows on the Mac: either natively on a partition of the hard disk (known as Boot Camp); or virtualised, within Mac OS X itself.

Three apps make the latter option possible: VMware Fusion, VirtualBox and Parallels Desktop. We'll be demonstrating the process using Parallels Desktop in the following walkthrough.

Virtualise XP on a Mac

You will need: Parallels Desktop Switch to Mac Edition (£74 inc VAT)

Step 1. First check that both systems are sufficiently well-specified for first transferring and then running Windows on the Mac. You'll need an Intel Mac running OS X 10.4.11 or later, and a Windows PC with XP SP2 or later. Your Mac will need 2GB of RAM and disk space to match that used by your PC.

Parallels Step 1

Step 2. Install Parallels on the Mac. This process should take less than 5 mins. When finished, eject the disc and load it into the Windows PC you're preserving as a virtual machine (VM). Run the Parallels Transporter program setup within Windows, and look out for the 'Parallels Transporter Agent' shortcut created on the desktop.

Parallels Step 2

Step 3. Connect the supplied cable between the two PCs (preferably between two USB 2.0 ports). Windows will state that it needs to find drivers for the hardware to work correctly. Click through the wizard to install it. If it can't find the driver, you'll need to install it manually. If it worked first time, move on to step 5.

Parallels Step 3

Step 4. Next, right-click My Computer and select Manage, Device Manager. Look under the Network adaptors for the Parallels Ethernet Adaptor, marked with a yellow warning triangle. Right-click this, then select Update Driver. Next, direct the installer to C:\Program Files\Parallels\Parallels Transporter Agent\Drivers.

Parallels Step 4

Step 5. Open Parallels on your Mac and you'll be presented with a welcome splash screen. Select Migrate to start Parallels Transporter. Choose Physical computer and Parallels USB cable when prompted. Run the Parallels Transporter Agent on the Windows PC to transfer the contents of your hard drive to the Mac.

Parallels Step 5

Step 6. Once complete (it could take several hours), click through the agreement to reactivate Windows. Have your original serial code handy; if Windows was preinstalled on the PC, this information should be listed on a sticker on the side or base of the PC. Launch your VM by clicking the Start button.

Parallels Step 6

Install Windows 7 on a netbook

You can install Windows 7 on a netbook by booting from an external DVD drive, since these mini laptops lack an internal one. But it's cheaper to use a 4GB USB drive. This will also be quicker and more convenient.

Install Win 7 on a netbook using a USB drive

Even with Microsoft's brand-new USB/DVD Download Tool, you can't just copy the contents of your Windows 7 DVD on to the USB drive and boot from it. Before you even think about copying Windows 7 to the USB drive, you must give it an active partition and make it bootable. Since many people will be upgrading to Windows 7 from XP, we'll use this scenario and prepare a USB drive on an XP-equipped PC.

Note that because Windows 7 can't be installed as an upgrade over XP, you'll need to use the 'Custom' installation option. This means all your programs and data will be lost. Be sure to back up all your data, programs, email and configuration settings first.

Because Windows XP sees a USB drive as a removable device, the Disk Management console won't let you partition it, nor make a partition active - that option will be greyed out. It won't even let you format it using the NTFS file system.

XP won't let you partition a USB drive

The easiest way to format the USB drive and give it an active partition is to use HP's USB Disk Storage Format Tool. This can format your USB drive using the NTFS file system, and it also automatically makes the formatted NTFS partition an active one.

To use it, simply select your USB drive from the Device list, change the File system to NTFS, select Quick Format and click Start. The whole process will take seconds.

To confirm that your USB drive has been correctly formatted, right-click My Computer, click Manage and then Disk Management. Your USB drive should now be listed with a 'Healthy (Active)' status, and it should say NTFS next to the capacity.

Before we formatted the USB drive with HP's tool, the status simply read 'Healthy' and the file format was FAT32.

Now the drive has an active NTFS partition, it's time to make it bootable. You'll need a Windows 7 DVD, and you'll have to get your hands dirty in the Command Prompt.

Windows 7 uses a loading program called Bootmgr. The active partition on the USB drive needs to have code written to its boot sector that is compatible with Bootmgr.

This code can be written to the USB drive by using the bootsect.exe program that is present in the Boot folder of the Windows 7 DVD. To extract this code, we have to use the Command Prompt. From the Start menu select Run, type cmd and press Enter.

Once the Command Prompt is open, switch to your Windows 7 DVD by typing the drive letter for your DVD drive (usually D). Then you must type the following line:

boot\bootsect /nt60 j:

In this line, we are telling bootsect to use the /nt60 command to write the compatible boot code to our USB drive, which is the J drive. Substitute the letter of your own USB drive for j: in our example.

Now that the USB drive is prepared, all that remains is to copy the contents of your Windows 7 DVD to it.

The root folder of the Windows 7 32bit DVD contains five folders and three files, and the entire contents takes up 2.32GB. This will take approximately 7 mins to copy, depending on the speed of your computer and the USB drive.

In order to install Windows 7, your netbook will need to boot from your USB key, rather than its hard drive. To change this, you need to enter the Bios and alter the boot settings. This procedure varies depending on the make and model of the netbook. To get into the Bios you'll have to press either Del or one of the Fn buttons. Look for a message onscreen when you first switch on the netbook. There will be an indication of which key or key combination you should press in order to enter the Bios.

Change the Bios boot order

Plug in your USB drive and switch on the netbook. Once in the Bios, go to the Boot menu and look for the Boot Device Priority' setting. Change the '1st Boot Device' option to USB. On some netbooks (such as the MSI Wind we used for this workshop), it may even give you the name of your USB drive.

Once you've changed the boot device, save your changes and exit the Bios. The netbook will now load from the USB drive and proceed to install Windows 7. When the installation reaches the point where it restarts the system, be sure to remove the USB drive, otherwise the netbook will boot from the USB drive and restart the installation.

Dual-booting Windows

If you've decided to make the move to Windows 7 but aren't convinced you'll be sticking with it, or are concerned about possible program compatibility issues, a dual-boot option is probably wisest. (Note, however, that Microsoft has done far more than it did when Vista launched to ensure program compatibility, and anything you can currently run on your PC should also run in Windows 7.)

To dual-boot a PC you'll need to partition your hard drive using a program such as Partition Magic. You need to create an NTFS partition and will require at least 20GB of available hard-disk space if you wish to run two operating systems alongside each other. Remember that you'll also need to retain a comparable amount of space for your existing XP or Vista system.

Once you've got a suitably partitioned drive, boot back into Windows and you should find a new drive in My Computer. Double-check you can open it. To install Windows 7, insert the disc as soon as the PC starts up or insert the disc while your existing version of Windows is running. When the screen appears asking where you want to install Windows, ensure you choose the partition matching the drive letter you've just created. Because that partition is empty, Windows 7 will perform a clean installation.

Should you subsequently decide that you want Windows 7 for keeps, it'll probably be easiest to delete one of the partitions, first ensuring you have all the drivers, documents and your programs backed up. A useful tool for reinstalling your programs on the upgraded PC is ninite.

Alternatively, if you're forsaking one PC and buying a new Windows 7 laptop or PC, you'll want to use either the Windows Easy Transfer tool or a third-party program such as Syncables or LapLink pcMover that help with the migration process.