I have Vista as well. It came with the computer. Personally, I wanted to stick with XP for awhile more, but meh, I didn't have a choice. I wasn't going to pay more money for XP either, so Vista it is, I guess.
I don't know if I like it or hate it, really. It is really pretty, which I like. The sidebar can be handy as well. On the other hand, a lot of my older programs screw up on it. For instance, Photoshop doesn't work quite right anymore. I have problems painting lines on the bottom and the right side of my files. I never had a problem on my older XP computer. My spellcheck for my LJ client isn't supported anymore, because for some reason it messes up in installation. Same with the software for my USB internet adapter (but it does work, at least)... and running the CD that came with my monitor. -_-;;
You have to get used to the new layouts and such as well, some of which I don't like either, but that isn't as bad as my older programs working. I can get used to new layouts and annoying popups when I install things -- however, I can't get used to not being able to use my programs like I used to.