You didn't mention your CPU, motherboard, or power supply. Do you already own a motherboard capable of supporting SLI? Along the same vein, can your power supply handle the needs of video cards? If yes to both, then SLI is at least a feasible option, and either solution would be great for gaming at 1680x1050. But they're really not in the same ballpark. GTX SLI is gonna run you $1000+ right now. Whereas GT SLI will push around $700+. Pretty big difference, IMO. And, there's 2 other big differences in the setups-- 1) the GTXs will be a lot quieter than their GT counterparts 2) the GTs are stuck with 256mb ram. I myself would've been all over the SLI GTs (cheaper ones anyway) if not for those 2 shortcomings. The SLI GTXs are just way out of my price-range.