Ok guys, thanks for the responses, but I have another concern, and that is the Warranty/ RMA service. I know that the XFX 7870 has lifetime warranty and from what I hear, they also have good RMA service, but what about the MSI 7950? Does MSI have good RMA service/Warranty's?
The 7950 has 50% more memory and bandwidth, and 40% more texture units and or 75% more shaders and texture units. Also, its core clock (880 MHz for your twin frozr) leaves way more headroom for overclocking than does the 7870's (1050 MHz on that XFX). Especially once you consider all that performance left on the table with the 7950's conservative clock (and remember, the 7970, which is essentially a non-gimped 7950, now has a version marketed at 1 GHz), the 7950 is a no-brainer. I mean, really. I would be offended if you got the 7870.
As for brand--this is a pretty thin reason to pick one card over another, and 3 years is totally acceptable. I like the lifetime warranty on XFX cards too, but are you realistically going to be using this thing for 3 years+? And if so, would you be that upset if it failed outside the warranty period? Don't give yourself at least three years of inferior video performance based on fear!
However, with all its OC headroom and superior silicon (as well as memory), you'll see a bigger performance gain over the 7870 on (1) newer games and (2) higher-resolution gaming. You can realistically expect an OCed 7950 to perform much more like a 7970: http://www.anandtech.com/bench/Product/548?vs=508 You can see the bigger performance gap at higher resolutions there, as well as with more demanding AA settings; that's the memory.