Well, at the begining of the year, my brother gave me an hp laptop with windows vista, and to tell the true, sometimes i was so bored that i almost throw it away. but i thoug, hey, the laptop itself is not the bad thing, its all about the os : Vista.
And then i tried to downgrade to Xp, and i almost had succes, except by the audio drivers, and the speakers that i never could make them sound.
So, without sound, how will i work? (i'm a dj and a musician aspirant). Well, the answer was, can't work with this, and if i want it to work ill need an alternative sound card, and they are not so cheap. So i had no choice, i recovered the vista os. and finaly and sadly i had to sold it 
But that was just one of so much issues that i encountered on vista, like, the slow performance in aero mode, some problems with the "new" my documents folder. Who really needs all of those folders inside? and when i tried to aplly the option to sort files in "type" mode, i had to search for that option in a big bunch of other options that doesn't work for me, and i think nobody else wants or need.
And maybe you'll think that's just a little detail that almost nobody put attention on. But as i said, im Dj and sometimes i want to sort my music files by type (you know, wavs, mp3s, wmas and so on).
But maybe the most destructive thing i encountered in vista is: there's no "up" button in the buttons bar. I use a lot this button when exploring my folders, but in vista, i always got lost, and to tell the true i dont use the back and forward buttons.
And there are a lot more bad things i found in vista, but i don't talk about them cuz they don't worth.
And to mention some good things of vista, i got to say that the new wallpapers are great, and the new windows aero interface is nice but i find side bar is not necesary. I ran acid music studio on it, and it worked well, but not so well with cubase and traktor.
I still use Xp on my now old pentium 4 HT PC, and i love it, and i just will upgrade to vista when i really have to by issues with new hardware or software that won't support xp anymore. but until then, i stay with XP...
Or maybe i crossgrade to a MAC. Mmmhh... sounds interesting to try new systems if microsoft follow developing bad OS's in the future.