The guy at the computer store was probably right, that is a pretty old graphics card and doesn't overclock too high.
When I looked up your model I found a few but they weren't exactly the same. I'm sure all of the AM1201's use the same motherboard, but I want to make sure. Can you download CPU-z and tell us the name of your motherboard? It should be AMD 740G, but I want to make sure.
If it is 740G it should be AM2 socket, with one PCI-e 1.1 slot.