If you change your mind, here are my two best suggestions:
190$:
http://www.ncix.com/products/index.php?sku=5624090$:
http://www.ncix.com/products/?sku=54933&vpn=AX4850%20512MD3-HV3&manufacture=PowerColorI may even be able to give you on of my old video cards I am not using anymore (7900 GS). Or sell you a much more powerful one (4850) in a month.
edit: But I am guessing your CPU is a single core... So that alone would be a bottleneck.