I've been havin gissues with my mac lately and I think it may be the video card. Instead of purchasing another ATI X1900 from Apple, I was considering getting a 4870 and modifiying it to work in my system. The main question is have is, how well does the 4870 perform on the Mac Side? I am a photographer and edit thousands of photos at a time often opening 50 or so images in photoshop at once. Is a modified 4870 going to compromise my ability to do this?