Bottom line is, for a reason I can't figure some people just dislike Vista.
I remember just as much crying and whimpering when XP was released. "I will never leave 98! XP sucks. blah blah blah"
Some things bug me about Vista, but overall its faster (assuming you have the right hardware) more secure (will get on to that in a minute) and just as stable (more so in fact for me than XP has been).
The new way it draws the screen, new networking stack, better (read night and day difference) between memory management, Aero, completely reworked networking stack, and more just make me love it.
As for security, I am the first to admit MS slipped up on XP, and I really do believe they are improving their standings on Vista. I have read an article a while back stating that Vista's security holes are actually patched and responded to far quicker than XP's ever was. (remember the RPC exploit, where if you connected to the net your PC was likely to shut down, or the messenger spam? all XP problems).
I am not saying Vista is the holy grail, it has faults, but as I type this now, I feel a lot more confident that my system will not crash, and will not get as much random crap installed thanks to the inbuilt security layers in Vista.
Oh yeah, and what about Mac and the linux distro's?
Well, first of all, MS have a far larger user base, which presents 2 problems.
1. People who know little about PC's will more than likely do things to compromise their security. I have seen it tons of times on XP. Annoying as UAC is (thankfully it can be made silent very easily) its very good for novice users because it warns them constantly.
2. Windows has a far larger share than Mac and Linux. This leads to:
A: More likely users will be infected through random viruses because they aren't protected and no little to nothing about PC's (Mac has as many less skilled computer users perhaps, BUT their numbers are far lower because of the amount of users compared to windows.
B: Because windows is so large, a lot of Viruses and exploits are written. Why write something for Mac when the percentage is a fraction of windows, for example?
With all of that said, do I prefer Vista to XP? Well yes I do. Do I think it's as good as it could be ? no, it has room for improvement. But still, to me MS have made a few steps in the right direction of Vista.