Quote Originally Posted by dgb
Uh, because you are going to have two sets of drivers, from different manufacturers fighting and trying to do the same thing. It might work flawlessly, but it's unlikely.
Well, the possibilities for problems are always there with computers - but if you installed both cards and drivers, the operating system should utilize the appropriate driver depending on which card is active. One card will be the primary (depending on motherboard settings), and should be the default at bootup. You should theoretically be able to enable or disable either card in the Device Manager (maybe reboot if necessary), so that only one would be active at a time.
That's the concept, anyway - not something I've needed to mess with, so only testing will tell.