What graphics card for my secondary computer?

[Guest]

So I've got a second PC, it's nothing special but gets the job done. Specs:

Core2Quad Q9550
P5Q3 MB
8 GB DDR3 1333
1 TB HD
120 GB SSD
Win 7 x64
Corsair HX1000W PSU

So I've got some nice stuff there. I also have 3 graphics cards I can use in it. I play some games (Batman Arkham City, GTA IV, WoW, Diablo III, The Witcher 2) on my TV (39" 1080P HDTV) and I'm debating what graphics card would be best with this setup.

I have a GTX 660 2 GB reference card, a GTX 560SE (yeah, not a great choice) and a GTX 570 SC. Just wanting to get some opinions on what would be best for this machine.

If I use the 660 I'll have to swap it out of my signature rig (main). So opinions are welcome as long as they are justified.

Thanks for your time, all!

 

[DeadGraphics]

Use the 570 I think it might do well in the build, if it will bottleneck then use the 560 no need to swap the 660 out of the main system