Forget about that graphic card, buddy. $teal something better,
MTA is a bit heavier than SP because of all the stuff servers put in (images, those shaders, blabla), so you better use something at least like a 6800?
Or perhaps go to a 8600GT! It's not expensive nowadays (i found some for 8€...), and you'll be able to play MTA maxed out at a fairly good resolution (e.g. 1280x1024) with volumetric shadows on, just without AA.
But really, going to a 6200 is... I'd rather play Nascar Rumble 2000 on my cellphone, thanks.