Capture cards for PCIe??

I am trying to figure out what capture cards I can use for a dual video input system. It will be the newer G5 tower with the PCIe slots. I am getting a blackmagic card for the first input, but I dont know what to use for the second. I have heard rumors that the two cards must be a different manufacturer. I am looking for a composite video input, although having SDI would be nice. Money isnt really an object, just something a with a good refresh is what we are looking for.

Any help would be appreciated.

Jason