I'd vote if I'd had issues with one of those combinations. I've had Intel+NVIDIA and Intel+ATI, no problems in either case unless a hardware component would wear out after several years of using it.
Sometimes I experienced issues with the latest drivers for my 2-3 yrs old cards, but rolling back to the driver from my support CD would always fix it.
To my knowledge too, the brand combination doesn't matter unless it's an obsolete motherboard with a brand new card on it. (Of course if bios upgrade doesn't help.)
~~~~~~~~~~~~
DirtRider, do you have RAM 3032 Mb, what sticks are this? (Just curious).