My biggest reasons for upgrading from Vista were pretty minor, since like most late adopters I had never had any real problems with Vista, but they added up:
(A) All my hardware was supported out-of-box (besides my tablet), so I didn't have to load down my memory with third-party drivers. (This is generally the case when upgrading to a version of Windows that's significantly newer than the computer, and probably the strongest case for upgrading in general.)
(B) My computer had come with 32 bit Vista for some weird reason despite being a 64 bit machine with four gigs of RAM (32-bit Windows can only use up to three), as well as the usual shovelware and add-ons that probably hurt performance. A clean install of Windows 7 solved both of those problems.
(C) I had already been using the beta and release candidate just for fun and got too used to the new features to want to go back. May as well get used to the new status quo!
(D) My hard drive semi-failed (I was still able to get my files off it but it wasn't practically usable anymore) a few months ago, forcing me to get a new one, and I wasn't entirely sure I'd even be able to get a full install off my backup DVD, so I decided to just pop the release candidate on. Which of course led to even more of (B).
(E) I was able to wrangle my way into getting it as a gift because I hadn't been able to come up with anything for my Christmas list.
In the end, it was a fairly easy decision to make. The fact that I was upgrading from Vista, which meant no loss of system resources (Vista and 7 have the same requirements, both way higher than XP) or backwards compatibilty (a TON of stuff that worked in XP breaks in Vista, sometimes in hilarious ways), helped a lot too.
Bob_F_It said:
Also, remember that Windows 7 actually has Windows XP contained within it (if you bought the professional or ultimate versions). So you get the best of both worlds that aren't Vista.
Sort of. You can
obtain Virtual Machine with XP Mode if you have Windows 7, but it doesn't come with. Same as the Windows Live Essentials.
EDIT: Oh, and one other thing. You know how they usually say getting a new version of Windows right away is a bad idea because it's always unstable until they've patched it up? That's not a problem in this case because Windows 7 is heavily based on Vista SP2's core, to the point of being basically just Vista SP3 with a price tag and some new features. Plus it had so many users during the beta phase that it's practically a year past release already.