Don't buy from Dell, buy an after market card from either an online vendor or even Best Buy. First, you need to know if your PC's video interface is AGP or PCI-Express...or with it being a Dell, does it even HAVE a graphics card slot? A lot of the smaller footprint desktop machines with built-in video are limited to using only the built-in video adapter.

That being said, a quick look at Best Buy's web site has a PNY GeForce 7600 with 512MB of DDR2 for $149 in either AGP or PCI-E.