I have a 8800 GT galaxy, i am interesting in doing SLI with any card which can give i HD or Full HD display & also increase me GPU preference, thing is that I don't want to sell my old card & secondly I can't afford 2 new card & I am quite interesting the in try this concept for multi card SLI have different card for rendering & PhysX acceleration.
Sorry but the sad fact your board doesn't support sli for the exception of a GX2 type card. You have little choice but to either upgrade to a single nvidia card that is better than the one you have or go ATI. Your board will do Crossfire which is multy gpu if you are interested.
For full HD gaming (1080p) the graphics card to buy in today's market is the ATI 5850. Price wise though, that is going to put you around $300 US at least. But it'll take an ATI 5850 to give you Good performance @ 1080p with high graphic settings (Of course this also depends heavily on what you're playing).
If that's out of the budget, you could consider an ATI 5770 ($155) or ATI 5830 ($215) as less expensive alternatives. You could run a Crossfire setup with 2 ATI 5770's, but for the money I'd rather have a single ATI 5850. Generally, I'd rather have the best single GPU I can afford, rather than two lesser cards in Crossfire or SLI.
5850 +1 if you can afford it while the 5750-70 for you are unable or unwilling to afford the 5850. I would avoid the 5830 due to poor economy for power and heat vs the 5770 and the 5850, also it is high priced. Avoid any thing less than a 5750 due to bang for buck since the lower end parts are over priced for the performance they delver.