Actually, depending on your final set-up, you might seriously consider the Mini-Pac
http://www.ultimarc.com/minipac.html for $29. It's basically an I-PAC/2 and half of an Opti-Pac on a single PCB board.
I highly recommend buying just the bare board and sacrificing a poor defenseless IDE HD cable and wiring it up as shown here:
http://www.ultimarc.com/mp_inst.htmlUPDATE - Also you need to use USB to use the optical interface on the mini-pac, but you would with an OSCAR mouse hack as well.