I kinda have the same issue as you.
I have a Atheros AR5006EXS in my fujitsu t4215. im have read that it is suppose to be a really good card, but in windows 7 in sucks.
I am able to get a a decent "FAIR" signal when i am in the same room with the router, but when i step into the next room the signal is gone. It can barely detect networks around the area.
I am using the latest drivers as well, 18.104.22.168. I have also tried 22.214.171.124, 126.96.36.199, and the 7.x.x.xxx. All the drivers yeild the same results Finding drivers for Atheros is a pain, since Atheros does not actually provide drivers. I do not think Windows 7 supports Atheros.
I just want to know is this an compatibility issue?
anyways i given up on the Atheros and bought a Intel 4965agn and will tell you about it, when it comes. they are cheap off ebay $13-$20, and has an 3rd antenna port. I am assuming with the correct drivers and an extra antenna, i should be able to pick up signals from houses away anywhere, HAHAHAHAHA