Is this graphics you are involved with, include 3d designing like 3ds Max and Maya etc. ? Well if you're getting into areas like that you'd definitely need a decent VGA card with good support for 3D. But the requirement will be more for gaming, where u'd need a heavier GPU ( graphics proc unit ).
Aprt from that I dont think u'd need a serious VGA for usual 2D or desktop publishing work like Photoshop, Illustartor and even Adobe Premiere, since almost all VGAs now have excellent support for 2D rendering. It's the 3D rendering part that they differ in capability.
In my experience I had to change my VGA from a 16mb Savagae Card to a GeForce 2MX (64 MB) which proved to be an awesome improvement in smooth running of 3ds Max.