Range problem with airport extreme card?

Hello,

I have an early Imac G5 running OS X (10.4) and I'm having trouble getting my airport extreme card (also old) to recognize my wireless network... I've tried with two different D-Link routers as well as with a brand new Airport Express base station and the routers literally have to be 1-2 meters away from my mac for it to notice the network at all. Right now, it's set up with the airport express in bridge mode (light is green) and my modem is an Aztech DSL605EU and all the right lights are on and the right color too....

This airport card has been connected to a wireless network in the past and worked fine (The router was a whole room away then! Woah!).... iStumbler tells me I'm getting 25% signal and 0% noise so I guess it's not due to interference... I've tried updating the drivers but no dice, and I can't seem to be able to reinstall them either... Any ideas as to why I'm getting such crappy range? Any suggestions as to what I could to to boost it a bit? Or should I just give up and accept the fact that my card has just ran out of "extreme"?

Thanks!