Well that depends, going with the 950 means getting an X58 and triple channel memory which drives costs up, but you get the advantage of having boards that can do SLI and Crossfire.
the 760 is cheaper, uses dual channel memory and uses a P55/H55 chipset. I think most of the boards are either crossfire or sli, not both but I'm not sure
(760 overclocks higher, though), with Hyperthreading (useless for gaming) with a triple channel memory controller, so the overall platform cost would be more expensive. Going with the cheaper CPU would allow more room for a faster 4GB of RAM and GPU improvements.
i7 doesn't need to run on triple channel memory. It's preferred however.Since the i7 has HT(Hyperthreading) which "simulates extra cores" by increasing perfomance and needs triple channel memory it's a lot more expensive so unless you're not doing a lot of programming and using CPU demanding softwares and mainly browsing, gaming etc. then go with the i5 760 since the overall performance will due and it is cheap. If you're worrying about the gaming part don't. HT which the i7 950 comes with isn't used in it.
i5.