What I mean is I have the parts already and was a bit worried about how the drivers would re-act to a new board, Graphics cards installed at the same time?
I'd have said everything together is your best bet as it sounds like your pretty much replacing everything so it'd save time when just doing a fresh install
Gotta be worth doing it all at once, because you're moving from Intel to AMD, I think - plus you'll need to install the S-ATA drivers on the fresh install or XP won't BOOT.