never had much luck with drop in wireless cards in my PC's. Always attributed it to positioning. Sort of old-school CB radio tuning. All that metal at the back--forming a ground plane that the signals are bouncing off of. More or less, you could be aiming away from your router without realizing it. Then there's potential weirdness with furniture and walls and what not that might be between you and the router if in another room.

Got my best results with a USB NIC for the PC's. Even the little thumb drive looking ones. Run a USB extension cable so that you can set that little dongle up on the desk, tape it to the window--sort of like running an FM wire up the wall on the old console stereos to pick up more radio stations. Man... talking about CB's, FM, ... I'm feeling old now.