Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
What graphics card are you using? I had the X1900XT originally and it kept freezing, got it replaced by Apple and it eventually started freezing again. I upgraded to the 8800GT and it's been 100% ever since. The X1900 is a POS...
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.