I know there are hundreds of threads on this already, but oh well. I prefer Vista because it has more "out of the box" compatibility, meaning you don't need to put drivers on a CD prior to reinstalling Vista, because it has almost all of the newer NIC's and wireless card drivers built in.
People who complain about it being a resource hog, obviously! Whenever newer version of software come out, they require more resources. Look at Windows 2000 to Windows XP, besides, if I spent all this money on a PC, I want to be able to take advantage of it, and not just when I'm gaming.