try reseting the CUDA switch on it (It's a button on the board. small square with a circular button in it)

Failing that, try a PRAM reset:

Apple+Option key+P+R

Do that at startup (as soon as you hear the chime on the mac)

failing that, I would suggest if you were to keep it, I would go get a PCI SATA Card and get either an adapter for IDE->SATA or a new SATA Drive. It's going to be better in the long-run over the IDE anyways.

Does it recognize the CD drives? What about if you put the harddrive on the secondary IDE (the one for the CD drives)

I thought some of these PowerMacs had triple IDE Busses