I'm going to upgrade from Vista, and just wondering about which version to go to. My main question is about backward compatibility vs future compatibility - the fact that you have to choose between 32 and 64-bit versions. The XP-mode available in Pro and Ultimate sounds like a good thing, am I safe to assume it works for old 32-bit apps to run in the 64-bit version of the OS? Or only XP64 apps? The run-downs I've seen state that the XP-compatability module require an extra gig of RAM (up to 3GB for 64-bit + XP - seems like a lot for an OS that's meant to be running leaner...) and extra 15GB of HDD space... Any main differences between Pro and Ult that would be worth the extra $100 or so? Finally, Hornet - I read in your monitor thread you got Pro really cheap... was that with the new computer, through you ed contacts, or... Thanks in advance for any advice!