So, I've got a dual 1.8GHz G5 with the Radeon 9600 XT, and I'm considering upgrading to a Geforce 6800 GT for $150. Thing is, I really don't have a need for this per se, it's just for fun. If I want to play games, I've got a PC with a Radeon 6770 in it, but it would be nice to game a bit better on this Mac since it's less of a hassle 
Not that it'd make too much of a difference, because most games seem to be limited by the 1.8GHz CPU, most PowerPC games aren't even multithreaded. So that's the problem, the CPU is a big bottleneck, and any benchmarks of the different GPUs out there use the high end (dual 2.3GHz and faster) models (to show off the GPU difference and not be bottlenecked by the CPU.)
Has anybody upgraded a slower Mac like mine to a fairly high end graphics card, and how that go for games? (like Quake 4, Halo, even UT2004)
Not that it'd make too much of a difference, because most games seem to be limited by the 1.8GHz CPU, most PowerPC games aren't even multithreaded. So that's the problem, the CPU is a big bottleneck, and any benchmarks of the different GPUs out there use the high end (dual 2.3GHz and faster) models (to show off the GPU difference and not be bottlenecked by the CPU.)
Has anybody upgraded a slower Mac like mine to a fairly high end graphics card, and how that go for games? (like Quake 4, Halo, even UT2004)