Your video card's RAM is independent of your system RAM, so it is not necessary to match them up.
It's not retail, but something like this [url=http://www.newegg.com/Product/Product.aspx?Item=N82E16814141026R]6800XT would be worlds of difference from the 6200's you've been looking at. Addtionally, a 7600GS or 7600GT would be a nice bang for the money if you look around a little bit. A few can be had for just a tad more and would also be a marked improvement over the 6200's.