I feel like "thanks" doesn't even come close to telling what I mean. I really, really appreciate you helping a noob out, man. You and other people who do this are what's best about the Internet. Cheers again, brother.
I'm keeping both options open (I'll order at the beginning of next week), so I'm just clearing everything up as much as I can. People have said the 660 might be better because of it being a NVidia board and benefiting from the PhysX and all. Your thoughts?
Having owned both sides, PhysX is pretty lame. I prefer Nvidia for their drivers but I'm also an enthusiast and power user. You could benefit from the extra performance of the 7870.
Just to update, I ended up going for the MSI GeForce GTX660 TF OC 2Gb GDDR5 Gaming, because it was the best deal I found. It's good, yeah? Thanks for everything mate!