Vista is just like XP.
When XP came out, EVERYONE HATED IT, they stuck to 2K, or 98 and REFUSED TO use it. When SP1 came out, it got a little better, and the transition (from 98, since lack of support) happened, then finally from 2K. Now everyone loves XP and despises Vista.
There's nothing wrong with vista, besides it being an extreme RAM whore, but turn off the Aero theme, turn off the sidebar, and you'll save A LOT of ram. That's basically why everyone hates Vista.
People say "Nothing runs on it", nothing is right, programs that are NOTHING, people who are too lazy to update it which are small, rare programs. I haven't had one program not work from my transition from Media Center to Vista. Even all my Warez cracks, keygens still run.
Overall, if you have a PC that comes standard with Vista, you'll be fine running it. If you are upgrading, use the upgrade wizard, to see if you'll be fine, THAT'S WHY THEY HAVE IT.
For me? I run vista amazingly fine, better then XP tbh. I can easily multi-task COD4, photoshop cs3, pidgen (im client), zune software, firefox, and no lag at all. I also have a quad-core pc, but if Vista was that horrible, I wouldn't be able to do that.
It's a great OS, and I all have to say if Vista is really all that terrible,
then why did it take longer to hack Vista then Mac Os x?