I happen to like Vista. I have been running it since Beta. It is a TON better since SP1 was released. I run 32-bit because I knew I would have driver issues if I went to 64.
I never tried running DVDFab on XP so I can’t compare it but it runs good for me.
All that being said, I wouldn’t upgrade to Vista on a old machine (anything older than 2007). There is a lot in Vista that takes advantage of new hardware.
And if you buy a new machine, get rid of all the crapware that comes on it. Half the trouble is all that stuff on there trying to load when you boot up.
If anyone cares, I have posted details about the Vista Media Server I built.