I was just wondering what the difference between the upgrade and full versions of WinXP are. I'd like to install WinXP Pro on a clean, formatted hard drive so will I need the upgrade or the full version for that. I'd prefer not to install WinXP on top of another OS. Does the upgrade version have an installation option where I can wipe my hard drive before the install? I currently have Win2K installed on my system. Thanks.