Honestly, that question leaves a lot to the imagination.
- Low power (I will be using the machine mostly for work, so don't want it burning through the electricity bill)
- Good performance (however, I would be nice to play to odd game from time to time)
- Dual DVI output.
- Not too expensive
With the exception of dual DVI output, every other criteria is fairly relative.
What do you concider low power?
what price range?
The 9600 GT is a good card for the price ($80 -$100) & does have duel DVI & of course Nvidia has the PhysX driver, but I am a Radeon fan myself. (person choice) The Radeon HD 4670 compares to the 9600 in benchmarks & cost about the same, although it's kind of difficult to find one with DUAL DVI. Most Radeon cards in the 4XXX series have 1) DVI, 1) HDMI & 1) standard VGA but thats what adapters are for.
For a few extra dollars you could bump up to the XFX Radeon 4770 which will give much better graphics performance but use a lot more power.
Personally, if my assumption of your situation is correct, I'd go with the Radeon HD4350 & a VGA to DVI adapter.
MSI makes a great card (I use it myself in one of my computers) that states it's required power is 300W. I've use a 250W for over a year without any issues at all. I've played COD Modern Warfare 1 & 2, Fallout 3, Farcry 2, GTA IV, & Crysis.
Radeon's Catalyst Control Center has a build in overclock utility which with one click will find the max capability of your system & push it to it's limit without any danger to hardware or software. I went from 6 Frames Per Second (Crysis) to 12FPS. Playing Crysis at 12FPS doesn't sound like very much fun but it works at low setting, looks good, runs well & for a $30 card in a stock computer it's pretty darn good investment to me.