5

As I replied somewhere else, now you have balanced rig, if you want to upgrade you will probably need to buy new cpu/gpu

really good but you kinda have a gtx 660 making it pointless to get xD

No

This is not a laptop video card o.O

Yes.

I dont belive so, if it dose maybe a bit, but why not check your mobo and see about droping an Fx-8320 in the rig if it suports 125W cpus, they go for about 160$

you could OC, IDK how much, but there is OC headroom.

Physx with an AMD gpu is dependant upon the CPU, which is really powerful (OC'd 3570k is awesome), 7870 is still an awesome graphics card, I'm pretty sure you'll be able to play most games @1080p with AT LEAST medium setting, probably high though.

Oh yeah, I know my GPU is still pretty powerful, and will still be viable for another year or so, even with new releases (although I don't own any games that run on the Frostbite engine, so I'll see how it goes with Dragon Age III). I've tried PhysX in the Batman: Arkham games a few times, and it's…playable…but it definitely cuts the FPS in half. I have Mirror's Edge, but I haven't really played it since I got this CPU last year. There's PhysX in that game, as well, and I remember using it on my previous CPU (AMD Athlon 64 X2 6400+ Black Edition), and the FPS was something like 5 LOL. Big mistake! I've got a really tame OC on my 3570k, so unless I OC it some more, I probably won't get much of a performance boost with PhysX enabled. Oh that reminds me: Does anyone know anybody who uses the AMD-Nvidia hybrid drivers (for AMD GPU with Nvidia GPU slaved for PhysX processing)?

Yeah should be all fine.
Although get an FX 6300 instead. It will perform much better than a 6100 and will cost much less than any of i5s ;)
if you feel like money is no problem I would say, go with an fx 8320