If you want to go entirly back to windows all you need to do is instert the windows disk, and answer "yes" until you get to the screen asking you about partions. The stardard method for a windows install (i.e. you won't later be dual booting linux-windows later) is to delete all partions and remake one large parttion, and tell it to do an NTFS format when it asks for the file system. I'm basing this suggestion of the XP pro installer, which havn't seen in about a a year and a half. It's pretty simple though.