OCTOBERDAY  Downloaded 5.4.1 and my airport card can no longer locate my Airport Extreme base station. After 8 frustrating hours of trying different things to fix it, I finally went back to wired connection to access internet. My card sees all the neighbors' locked wifis, but not my Airport Extreme base 3 feet away (which, by the way, it can "see;" It's listed when I go to 'advanced.')

I have an older Powermac G5 Dual Processer, and I'm off warranty, so am waiting for some good advice or a bug fix. I can't afford to pay tech support to help me fix Apple's mess-up...  
(Version 5.4.1)