Even your 8800GTX could do Physx with cuda.
It is up to you if you want to keep both.
Do you play allot of games with Physx? If you do, it may be worth doing some benchmarks to see what works best for you.
AGEIA PhysX processors users should use and install older PhysX system software such as version 8.09.04. Note – AGEIA PPU acceleration support for 2.8.1 SDK or earlier, and Windows Vista and Windows XP only.
Yeah, maybe just take it out...