I'm mostly happy with my new Mac Pro, but wanted to add some more video ports to support the IBM T221. I tried adding an OEM video card, but the OS would not recognize the card.

When I first booted the machine, the PCI Express Lane Utility recognized the card and offered to let me change the settings, but even after plugging in the extra monitor ports, no luck. I tried to use the MacVidia 1.08 driver at http://macvidia.starchaser.org/ , but that crashed on boot. Within about an hour of posting on their forums, a couple of very helpful responses were received and it became obvious that the problem wasn't their driver, but that I was misusing it. Even if everything was working, it's not designed for multiple video cards, and it's not an optimal solution because it doesn't yet support OpenGL, for instance. The thread is here if you want to review it.

Thankfully, the MacVidia installer created a backup of the old .kext files in the root directory, and I was able to boot from CD, remove the files that it added from /System/Library/Extensions, then move the backups back to there. When I rebooted, I had lost my old display settings, but was certainly happy to have the machine running again.

So while MacVidia may eventually support such a configuration, it's probably cheaper to just get the Apple label version of the card. This Froogle search should give you the approximate best price for it, which is 65% more than I paid for the OEM card, but would have been worth it for the time.