The memory will help, but I truly believe it's NOT his major problem. The 9200c is one of the worst mistakes ATi made in making a card. They know it and the 9200 series was quickly discontinued.
Howard I would look at ridding yourself of that card. I am an avid ATi fan. I would recommend looking at newegg.com for a replacement. You don't have to spend a whole lot to get a far more superior card. Maybe $100-$175 range should get you a late model 9800 Pro or even an X600 or something.
I would assume you have an AGP slot. Be careful when shopping for a card now that PCI-Express is out it can be confusing. Make sure it's an AGP card. Also check Ati.com for latest Catalyst drivers, I believe 5.9 is now out. Driver updates will keep performance higher.
If you have any questions or need help send me a PM, I would be glad to help.
AstroSteve 