Probably not with your motherboard, some are SLi-Capable, but SLi's more of a rich man's game, you get better performance per pound with single cards. Unless you're combining two of the top end card like an 8800GTX to get additional performance, SLi's a bit of a gimmick.
They're all made by different companies. While the technical stuff underneath only gets designed and made by ATi/nVidia, the actual board, and therefore product is made by a load of other companies, agreed by ATi/Nvidia as partners. For example, Sparkle, XFX, Gainward, Leadtek, EVGA and BFG make NVidia products and Sapphire, Gecube, Connect3D, Club3D, HIS and Powercolor make ATi cards. MSI and Asus make both. The differences between them may be that they're overclocked, what cooler they use, what cables and software are included and what colour the PCB is, but at the end of it, you're buying the same product made by different people. I usually recommend going with the better brand names for Graphics cards, they're better put together.
For NVidia, EVGA, BFG and XFX are the ones to go with
For ATi, Sapphire, HIS and Asus are the ones to go with.
Despite the fact that I told you the 7600GT was better and cheaper?
I hope you paid less than £57 for it, because it's significantly slower than the 7600GT I pointed you to at ebuyer.
Sli refers to the technology I was just discussing. It lets you use two graphics cards in one PC. For low performers like that card, it isn't necessary.
As for the thanks, You're welcome but perhaps you should pay a little more attention to what I advise you next time. The decision you make is your choice, but in going with what seemed like a good deal, I feel like you've lost out.
If it's any consolation, that card will be significantly faster than what you got with the PC off ebay.
I think the 7600GT performs even better than the 8600.
EDIT: Sorry I was just looking at the end of the first page, so this comment is not even needed.
it will be able to play every game that comes out at least up until 2008, even if not at high detail settings, or at least it would with a 7600GT. With the much slower 8500GT, it may struggle with one or two titles, and there will be games coming out this winter that probably won't run on it.
