I have always used Windows, until I recently bought a mac laptop. I use both computers equally (and I even downloaded windows onto my mac, so I have an option of switching between OSs) and I find that thought mac is easier to navigate and has less viruses, windows has many more programs (true..many more bugs) but if you want to use certain programs, you can only use microsoft.
I think Vista will target some major downfalls of XP, but I also think that it will have tons of bugs. It seems that the only programs I have trouble with on my computer is the programs made by microsoft, so I'm interested to see if they update the bugs in Windows Movie Maker and programs like that.