Signal Strength Low?

I've got a wireless network set up at home (Netgear FM114P router with two PCs connected through Netgear MA311), but one computer is recieving a very low signal strength (and occasional random disconnects, and it's only about 30ft away from the router), the other one (only about 5ft from the router) gets excellent strength. I went as far as to disconnect anything that works on the 2.4ghz range to interfere with the signal. I gave the NIC a static IP, made sure both the router and NIC were on the same channel, double checked all settings and I'm still getting low strength. So I went out and bought a wireless adapter (Netgear MA101) and set it up on the desk of my computer (the one with the problems, the NIC card faces a wall on the floor) and I get a very good signal strength.

So I've eliminated everything I could think about that could be the problem (even tried zip tieing cables out of the way), except for EMR since my case is plastic not aluminum. Is it possible that my PC can produce enough EMR to interfere with the signal? Or does anyone else have any ideas as to what could be the problem?

Is it possible to buy an a new antenna that sits apart from the NIC card? (Something I could put on top of my desk and run a connecting cable down to the NIC card)

hyperlink.com sells extender kits for as low as 30 bucks before shipping. 5 dBi omnis with short pigtails but it doesn't sound like you need a long one anyway.