You just need to boot up with the XP disc in the drive (make sure the cd is set to be read before the harddisc in the BIOS). It should say press any key to load from CD, this will take you into the initial screen where you have 3 options. Choose the first, then select the partition you want to install on, as it is a new harddrive you should only have one. Select this partition and it should ask you to format it and to choose which type of file structure, I would recommend NTFS especialy if it is a large harddrive. The computer will then need to re-boot and will then start installation. You won't need access to the internet straight away as you have so many days before you need to register, so you can set up your ISP first.