Thanks folks.
Think I'll get one from Dell... Gonna have to have a proper look into the XP versus Vista thing. Guess I was hoping that people would say - "Vista was rubbish early on, but now SP1 has come out things are much better"... It kinda seems daft buying a new computer with an old operating system on, which Msoft will probably stop supporting in a year or so... But if Vista really is that slow, maybe I'm gonna have to do just that...
(If it was just for me, I'd be very tempted to have a look at Linux... But for the person this computer is for, that really wouldn't be a good idea...)