As myself and many other techs have already found out,
many of the new pc's today are made up of hardware for which there are NO XP drivers and never will be.
So backing up to XP on those Vista PC's is totally impossible.
I'm specifically thinking of a little HP laptop that falls into that category.
So if you don't want Vista, buy a computer that comes with XP installed.
I just installed a cute little eMachine (Mini Desktop) last night that was purchased from Wal-Mart, with XP installed.
That's the only retail store that I personally know of that's still selling XP loaded PC's.
Good Luck,
The Shadow