@newsense:
OK, that's another thing - > you have a signal, but weak! Now, that behavior is reported since MOS supports Mac's internal WiFi - that is'nt new - even first test-devices had that problem....but CardBUS-cards are not affected - they work well. I'm writing this lines on a PB with a Netgear-Card....
The reason for that weak signal with internal WiFi is'nt known till yet (afaik) - there seems to be something undocumented in programming Airport....