Hello, I First want to let everyone know i do not have a preference in ATI/Nvidia None at all
Here is my Current setup
Motherboard- Intel DX58SO
CPU- Core i7 920 No Ocing Stock cooler (Possible upgrade soonish)
Ram DDR3 6 GB Triple channel 1600
Hard Drive 4X Internal 7 External Total 10.7TB
Optical Drives- 1X DVD Writer
Current Graphics card-8800GT Alpha dog edition From XFX (Core 670 Mhz /Mem 975Mhz/ Shader 1675Mhz)
600 Watt Power Supply
My Monitor at the moment is a View sonic running at 1680X1050 (Also possible upgrade Soonish)
Now even if I get a new monitor the probability is that I will stay around the same resolution
Here are the two options i was thinking
Now if i go with the Nvidia option Will I be able to use the my 8800GT as a dedicated Physics GPU? (Not sure if it's really worth it anyway)
Also I have a budget around 320
Games that i play or plan on playing
Duke Nukem forever
Medal of Honor
Call of Duty Series
You don't need to spend that much. Even a 768mb GTX 460 should be very good for your resolution and is a good deal. It is nearly twice as powerful as your 8800GT at stock and also easily overclocks a very large amount(usually 30%+.)
Then again you could wait a bit. The first HD6000 cards should be out on the 22nd and even if you still go for a GTX 460 Nvidia supposedly already plans to lower prices of the card in response.
You can use the 8800GT for PhysX but I wouldn't bother personally. Only a handful of games use GPU accelerated PhysX and none of the games you mentioned do so. Perhaps keep it around as a backup card and throw it in if/when a PhysX game you actually want to play shows up. Otherwise it will just be sucking up power(30-40w at idle) and raising your power bill for no real purpose.
The 768mb GTX 460 would be a fine choice for that resolution as I can max out damn near everything with mine using a core i3. But if you plan on stepping up to a larger monitor, adding another monitor, or adding another card for SLI I'd strongly suggest the 1gb GTX 460. And if you do decide to go with an ATI card you can still use your 8800 as a physx card. It is blocked by default by Nvidia, but it will work with a driver hack. Google hybrid physx.