SLI was introduced first with 3DFX Voodoo 2s, and the called it Scan Line Interleave. Ever since nVIDIA bought 3DFX, the terminology changed, now being Scalable Link Interface. Well, getting SLI it's a mixed bag if you ask me. Sure, with today's games, it doesn't take much to notice the benefits of having two cards connected through SLI, since the workload is split 50/50. SLI is expensive, since you need to buy two cards instead of one, and the cards used for SLI need to be identical. I'm not the one to say whether or not Crossfire is going to dominate over SLI, but ATi's move was expected after nVIDIA introduced their PCI Express SLI cards.