When I launch Maya my machine freezes and goes into not responding mode and while doing various animations I get the same issue. Soime one told me to upgrade my video card and my question is should I get a 1gig, 2 gig, 3 gig video card.
I doubt your graphics card is the actual issue. I've run Maya on ancient laptops without any real issues. Sure, it didn't run all THAT smooth, but it ran, without freezing. As far as I know, Maya doesn't use your graphics card all that much (unfortunately), if at all.
I can't tell you what the issue is, since it could be anything judging from the information you provided. But I wouldn't start spending money on a high end graphics card only to find out it wasn't what caused the freezes. Those things are expensive as hell.
That said, I'm confident you have sufficient memory in your machine. 4gb will do, 8 is good, 16 is excellent.