airport extreme station - connection drop

[mackinaw]

hi I have an airport extreme base station, one ibook (G3, 600MHz, 256 MBRam) and one dell Inspiron 600m with: "integrated dual band j(802.11 a/b) antenna, integrated Intel® Pro Wireless 2100 802.11b miniPCI wireless card."

the PC has a long-standing problem: it gets the connection for 2-5 mins, then drops it.

the ibook has been fine till about 2 weeks ago, when it too started dropping the connection every hour or so, and not seeing the connection for 5-10 mins.

A friend was visiting recentlly with a wifi pc notebook, and he too had major probs staying connected, so it must be a problem with the base station.

I've tried:
-a reboot of the base station
-a refresh with the airport utility.

any other hints? Thanks!