Oi, Wireless here. Using "G" type config, with an ASUS p5k motherboard built in chip, I'm getting excellent singal. The router is like 10-15meters away with two about 15cm thick walls in the way.
Getting about 1,2MB max download speed, with 20MBps connection. The router sometimes DC'es but that's because it's crappy and overloads from the amount of torrent connections.
Judging from my experiences - it's purely software/setup issue. I would recommend checking what type of network are you using (should be "G" or "N", eventually g/b mixed mode - anything else means you're screwed). Also check your router if it's not doing anything funny, like limiting the bandwidth on purpose (QoS options).
apple router
Nvm, all that i wrote, that's probably the reason. Now I even doubt that you will be able to access the router's control panel... Even if, it's worth checking, what kind of funny stuff apple did there by deafult.