As I rather expected, after half an hour or so, my main computer announced that there were no wireless networks to be found, while the other box (an identically-configured Dell Inspiron 600m familiar to some of you as the computer that normally powers the sound FX for Match Game SF but usually lives on top of my television set downloading rugby matches) continued to stay connected to the flypdx free wireless at Portland Airport. I think that if time permits while I'm up here, I'll do some more troubleshooting to see if I can further isolate the problem. For instance, I can do a "brain swap" by swapping the hard drives in the two computers just in case there's some sort of software problem (which seems unlikely, but I'm trying to close off all possible lines of evasion of responsibility from Dell's Hardware Support line). Having two identical computers makes this pretty easy, since everything is compatible. Assuming that confirms that the fault is in hardware, then I can try actually swapping the wireless cards and see if the problem still happens on the same machine. If it does, the fault is probably with the antenna rather than the card.
Meanwhile, I just got a call from Lisa's father telling me that she got underway a bit later than she originally expected and that I should hang tight for a while longer. That's okay with me -- I'm reasonably comfortable here in one of the PDX "Service Centers." The only minor inconvenience is that, as I'm traveling alone, when I need to go use the restroom, I have to pack up everything, there being nobody to watch my stuff for me.