LOL, well not all cards work in all Macs. You should try to change one in an iMac or a Mini!
iMac isn't that hard, but mini... it would be a real challenge
Hey Sheep, was the MP1,1 you tried it in soft-booted in 64bit? I thought you just tried it ina 32bit system and thus didn't work... Is that wrong?
I've tried all possible ways in my 1,1:
32-bit 10.7.5 (Sapphire drivers)
64-bit 10.7.5 via Chameleon (same as above)
10.8.3 via Chameleon with built-in drivers
More details here.