More memory is more better. That seems like a good price. Check out New Egg.
>add another video card to another rig in our studio
Do you mean you are going to replace an existing card, or add a second card?
If you plan to add a 2nd card, be aware of potential problems
2 cards and 3 monitors http://forums.adobe.com/thread/875252
Dual Card SLI http://forums.adobe.com/thread/872941
A PARTIAL comparison of nVidia cards http://www.pacifier.com/~jtsmith/GPU.HTM to compare cores and power used
Upgrading second machine john. Thanx for info as well.
[moved to hardware forum]
The 570 only supports 2 monitors, the 660 up to 4, the power consumption of the 570 is far worse than the 660 and the performance difference for PR is negligent, so my choice would be the 660.