Pci slots

I have a computer with an ASUS P2B motherboard and am trying to install a Netgear WN311b wireless adapter for my 802.11n router. The LAN pci card that I pulled to install the wireless card had a single alignment notch while the Netgear pci adapter has two notches. The only requirement info I find on the card says pci config. When I install this adapter in my motherboard, the computer will no longer output any video whatsoever. If I pull the card, video returns. If I reinstall the LAN card, video returns. This is the second one of these I've tried. The seller agreed that maybe the first one was DOA. Netgear tech help has no useful advice about the possibility of their card being incompatible with a motherboard as old as a P2B. Can anybody tell me if there's a difference in pci cards that have 2 vs 1 notch or if there are different kinds of pci slots?