Predictor, Are you sure you don't have an AGP slot? I'd say just about all PC's shipped since 2nd half of 1998 have AGP. Anyway. With two PCI graphics controllers vs one dual PCI controller, I'd suspect that you'd see slightly better performance using two cards. The only time you'd see much of a degradation using two cards, is when a window is moved from one monitor to the other (forcing a PCI data copy). That's probably outweighed by having the hardware rendering running in parallel. You'll also have two cards arbiting frequently for the PCI bus, which is a relative expensive operation.