I certainly would not reformat just to change video card brands. As allcott and Mike say, a clean system (as in "housekeeping") is all that's needed. I went from nVidia to ATI almost a year ago and had no problems. I used pretty much the same method outlined by Mike a few posts up.A clean registry = happy computer = few if any hassles... anytime.

I heard and read a lot but to reformat a whole HD or to reinstall a complete OS for changing a vga card is just out of the loop...With all respect they are quite misinformed hmm... as a MCSE stuff guy I'll think they should stop giving advice...Just de-install the nVida drivers and start up in standard vga...Install the Catalist drivers and that's all there is to it ;-)I'm happy with my upgrade from G4TI4200 to 9800 Pro 128 mb :-)Have fun with your new ATI...Andr

It's a good idea to open the regestry HKEY_LOCAL_MACHINESOFTWARE and delete any reference to your old vid card.David

A reformat is not for getting it to work it