No one should be suggesting any 8800 to you at this point. That card is years old and all of the 8800 cards were given new names long ago(8800 GS = 9600 GSO, 8800 GT = 9800 GT, 8800 GTS = 9800 GTX = GTS 250, ect)
What card you should get depends on that resolution you will be using. Also we will need to know what brand/model your PSU is to tell you what card your computer can handle without a power supply upgrade.
I can tell you that you would need 3 8800GTX cards to equal 1 GTX 275. Even a GTX 260 would be better than a single 8800.
I would almost feel safe recommending the ATI 5750 if you want a low power cosumption card with decent power to run current games and some future games.
You can pick one up around 129.99. I just ordered the 5770 for my media center setup and these cards get great reviews. The only bad thing with these cards are the 128 memory bandwidth limitation ATI appended to them to make them fit into the market segment they were trying to fill. They say since its DDR5 it balances out.
As jyjjy said, post your configuration hardware so we can be positive on what to suggest...