1. Back up all your data files, and make sure you have all the software disks that you need, and that they are WindowsXP compatible.
2. If you have things like network cards, printers, scanners, modems etc., make sure that you download WindowsXP drivers for them prior to changing the operating system. Save all the drivers to a special folder on the hard drive, and then transfer them to a CD or to floppy disks.
3. Save all emails that you want to keep, and save your contact list/address books. Save them to floppies or to a CD - this is very important.
4. When you're ready, put the WindowsXP disk in the drive and let it run. When you are asked if you would like to upgrade the existing installation or perform a clean install, select the clean install. This will erase everything on your hard drive, so make absolutely sure you have got everything you want on CDs or floppies before you start.
5. Sit back and watch, or go for a meal - it will take around an hour or so to install and configure WinXP.