Its really easy actually. The key part would be making sure all your data is backed up. Adding a new drive is not a bad idea. My PC has 5 drives in it, and one of those drives is only used for the operating system and applications. So, if I ever need to reload, I just load Windows to that drive, reload drivers and apps and I am done. If you have a Windows XP CD, put it in the drive, and you should be able to boot off it. You may have to set you BIOS to boot from CD. Then the Windows install will begin, follow the prompts and format the drive when you get to that point.

Bart