My desktop dual boots to either 32bit XP or 64bit Vista, and my new laptop came with it. Its fucking awesome, I'm sure on some older machines it runs like shit, but it craps all over XP... everyone always compares it negatively to OSX / Leopard, but is it actually better than XP? I'd say so, yes.
More secure operating environment. Idiot proof (UAC is optional). Takes better advantage of multi-core machines. Searches your network more intelligently, supports the IPv6 protocol already. I have one printer in this house, and all the other computers use it. It was easier connecting to it with Vista than it was with the other machines. Incorporates the tablet features of XP Tablet edition and improves on them. Has shit-hot voice recognition, although I can't see when you'd use it. Windows Media Center built in. With or without using the Aero theme, it just flat out looks better. Everything is indexed, search speed is improved, you can now just hit the Windows key and begin typing whatever program / file you're after to get at it instantly. Speed has improved for games and stuff from SP1 onwards too. I'm sure there's tonnes of other shit I've missed out.
On the desktop system with 64bit Vista on it, I did have some teething problems, while I waited for drivers and things like that, but compared to the last 64bit system I tried (XP64) -- again, it shits on it. Any 32bit programs run just fine.
