what's your resolution? if your running a high Res with settings.maxed out your 5850 may be struggling. I know that doesn't make sense since the graphics are so poor you'd think it'd be OK. but you never know
Hell no! MW3 is so bad on PC I'm not even kidding. I guess some like it, but it's just terrible on PC. Black Ops and MW1 are 10x better. Read my review on metacritic if you want more detail, it's the one rated "Most helpful"