I too have an AMD 3200+, 2 6600GTs running in SLI and 2 gigs of memory on a socket 939 mobo. I don't want to buy a new comp either, so my solution is to up the cpu to 4000 and add an 8800gts. The vid card will transfer to a new machine down the line.
The AMD 4000 is available used on e-bay for around $40, and the 8800gts can be obtained for about $266 with a rebate:
8800gts:
http://www.clubit.com/product_detail...OTC-pricewatch