I have seen several reviews recently, both on line and in print that show two 8800gt cards in SLI performing very well indeed. If you could get a second at a good price i would go that way. If it was going to cost close to a newer card i would get the newer card 9800GTX(+) or HD4850 and sell your GT on.
i think throwin in another 8800gt would be your best bet
jealousy >: (
try to get another 8800gt that is equivalent to your current 8800gt though becuase the system will automaticly choose the lowest clocked card as the default speed for both cards.
and oh yeh, setting up multicard configs is a pain in the butt as far as installing drivers goes.
had "tons" of fun trying to get my 3870s in crossfire
8800gt is still an awesome buy though
if it were possible, id sell my 3870's and buy a pair of 8800gt's but i cant cause my board is only crossfire
maybe someday i will built an intel/nvidia rig like you V3NOM