you dont have to go all out and buy a new comp just for a graphics card and a stick of ram.

upgrades- yeah you should go for ram, but depends on what you are going to do! If you want to do a lot of rendering of complex scenes, stuff that, i dont know, takes 3 hours or more a frame, you should upgrade your processor too. But still, if you upgrade, go for the ram. You should have one, if not even 2 gigs of ram for stuff like maya.

And graphics card, i'd go for the NVIDIA Quadro FX series, though most of them have prices that go through the roof, for graphics, they are great.