Go with the ATI... while there's nothing out there stressing those cards today, there will be by the end of the year if gaming companies hit their release dates.

Other than the very newest Geforce card, which is very nice (and 400+ bucks), the NVidia line has been underperforming since the Geforce 4 came out, and their early GeforceFX boards were hot, loud, and slow "also ran's". I'm glad to see that NVidia is finally getting back into the ballgame, but ATI is going to have a new chipset out shortly, so they may be back to second rate after that happens.