u need to use a interface chip for the pci bus ...e.g plx 9052 .. u can go to www.windriver.com or www.plxtech.com to get more info for these chips...what these chips do is just act as an interface between the pci bus o the pc side i.e pci master and the evice on the other side i.e a slave in this case a 8051 microcontroller ... u have 2 take a little care n effort in the development of the card n thats it