I'm curious about what-effects-what in my computer. Over the past couple years I noticed some of the video like YouTube or will stutter and hold during times of "high computation". If I open a web page while YouTube is playing, YouTube stops for a second. Can this be remedied with a new video card? My system still has the original 1900xt which is said to be pretty crappy for a variety of reasons. What kind of newer card can I get for this Mac? Does the 5770 work well and what kind of improvement would it provide? Thanks.