I had a search around for an answer but cant seem to find the thing i want, Sorry in advance if it is already out there somewhere but...

I want to get Vista, Ive run the "Windows Upgrade Advisor" and it says i am able to "Upgrade" to Vista, But i dont understand the 2 copys that around out, "Full Version" and "Upgrade" - Can i buy an upgrade copy to upgrade from XP? or do i need the Full Version?

Thanks in Advance,
Tom.