old processor, new graphics card.

I have a Dell Optiplex GX620 with a  P4 3.4GHz processor and a Radeon x600 SE graphics card currently. I would like to upgrade the Radeon to something not as shitty for games, so what would be a good card that wouldn't be too much for an aging processor I can't upgrade? I'm thinking about a GeForce 9500 GT as seen here: http://www.newegg.com/Product/Product.aspx?Item=N82E16814150322

Before it's suggested, the only processor upgrade my mobo will support is a Pentium D, and for some reason I can't find those anywhere.

x850 maybe but even then I'm sure it will be slowed down by your cpu.  I think it's not worth the time and effort finding these ancient pieces for very small gains.

Save up and go e5200 and ATI 4830 for a decent price/performance ratio.