I want to buy a Multiface II. There are plenty options to get it new, but since I have a brandnew PC I think I want a PCIe card to get it connected. What is the difference between both and does it make any sense to spend the extra money?

Windows PC -> Core i7 4x 2,8 GHz, 12 GB Ram, Asus Workstation Mainboard (no soundcard yet)
Macbook Pro -> Core2Duo 2, 2,4 GHz, 4 GB Ram, RME RPM, HDSPe