Amin Inshassi asked theDesktopsforum for details about what can and can't be done with a virtual machine.

In a virtual machine (VM), software pretends to be hardware. You can thus load a "computer" into a VM application the way you can load a document into a word processor. It was through a VM that I grabbed this Blue Screen of Death image.

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I can recommend two separate VM applications, both free. The easier of the two, especially if you're just learning about VMs, is VMware Player, the stripped-down version of a much more powerful and costly tool.

Oracle's VirtualBox can do more; it's useful snapshot feature makes testing much easier, and it's much better at booting from external media. But I find it trickier to use.

But you have to understand that virtual machines are not a virtual paradise. They come with all sorts of problems.

Let's start with the most obvious limitation: A virtual computer can never be more powerful than the real one that it runs on. It will always be slower, have less physical RAM, worse graphics, and fewer gigabytes of storage. You can put a sedan inside a truck, but you can't put a truck inside a sedan.

But there are other, less obvious problems. For one thing, it won't be on the same network as everything else. Yes you can set it up to share files over the LAN--a process that involves installing special software in the VM--but the setup will likely be problematic. Sometimes, it won't work at all.

Fortunately, at least in my experience, getting on the Internet has never been a problem.

If a machine doesn't exist in the real world, it can't possibly have any USB ports, making it difficult to plug in a flash drive. You can, of course, plug the drive into the real computer (called the host). But then the host takes control of the drive. It takes a couple of steps and some waiting to "connect" the drive to the VM. That doesn't always work, either.

I do a lot of software testing in VMs. But it's not unusual for me to give up and test on a real computer. It's faster and has less issues.

One more problem: Unless you're running Linux in the VM, you'll have to buy another copy of Windows for it.

Read the original forum discussion.