Vista is really good, the best so far, by far. It's not the best OS for every possible use, but no OS is. I think it's the best OS for (decently configured) home desktops. It could be leaner in order to be the best laptop OS, I think Mac OS X is in a lot of ways the best laptop OS (definitely not the best desktop OS, since it doesn't do the basic things a desktop OS should... which is to let you run the hardware you want and the software you need).
Vista 64-bit... the horrible HORRIBLE Vista 64-bit is what I run. And I truly don't get what people are whining about. I mean it's GOOD. I run Bioshock, Gears of War, Call of Duty 4, Quake 4, Doom 3, Psychonauts, every game I've tried so far... basically, just perfect backwards support. I run Adobe CS3 and Office 2007 (which is really strange at first but grows on you in an odd sort of way). I also play Bluray movies on it (entirely impossible to do on Mac OS, period). It supports the best video cards (and DirectX 10), the best available hardware, it supports overclockable hardware, cheap or expensive hardware, etc. etc. It is a fantastic OS for the year 2008, and will be for 2009. My desktop has more hardware than I know what to do with, and I think that this is quite typical. Vista helps to tame great hardware and make it useful... all that an OS can or should do.