PCI cards will fit in the PCI slot, no matter what pins are enabled on it or not. PCI-x cards will also fit a PCI-x slot, as long as the notch matches the one on the PCI-x slot. PCI cards do NOT fit PCI-x slots, or viceversa.
In brief, if you have PCI slots available, it should work.
For compatibility, check this:http://www.soundonsound.com/sos/feb08/articles/qa0208_4.htm