I read an article once about someone who experimented with 800x600 on a CC and got it to work, but only for a few minutes before he switched it back to 640x480. It might be possible that a CC can higher than 640x480 from this, but this guy didn't want to risk blowing up his video hardware, so someone else will have to be brave and try 800x600 for a longer test period to see if it is stable.