Actually, doing a complete reformating of your puter is preferred.. it is very simple to do for XP. You take the disk. Insert it in the puter. shut off puter.. and restart. it asks two questions similar to are you sure you want to? YES. It will delete everything on the HD.. Yes.

Definately make sure you back up the files you want on your puter that you need. Such as pictures and recipes and anything you created on your word programs. You can always redownload Spybot. And for free virus software AVG
Like any other virus software though, you can't have anyother virus software installed.