Technically the GTX260 is above the minimum requirements - but personally I wouldn't think it would run very good based on how the game seems to be optimized. You would definitely have to stick to lower resolutions. What is the rest of the hardware in your system - processor & RAM?
Minimum requirements: http://community.callofduty.com/thread/200786048
Edit: Woops. Didn't catch the DirectX 10 spec. In that case it actually isn't supported even though it is above the GTS450 in performance.