Well, did you try any other client cards?  I know you're not interested in using them permanantly, but for troubeshooting sake it might be good.

Also, just to give the company I work for a little plug, check out the wireless test tool that we make... http://www.cmc.com.  It's for AP manufacturers to test their products, but also seems like the product would do well for system integrators/installers.

-CaP