If you have a MacBook with the X3100, I'm sure it can handle that fine. My MacBook has a GMA 950 and I notice that if I am watching a movie in 1450x1200 (if a remember correctly) on my 17" Apple CRT while I'm doing other tasks on my MacBook display, the fans tend to kick on quite fast. I've also noticed somewhat of a slowdown in animations in OS X during this time. This could all be because I am watching a movie though while doing a bunch of other tasks.