This afternoon, the power went out at work. I think that something during this outage caused my 802.11g PC card to get fried. When I got home, the card wasn't recognized at all. I rebooted without the card installed, and was able to use the built-in 802.11b card.
Unfortunately, this means that when I do large file transfers, things will be a lot slower. I guess I will just plug into the wired network for these transfers. But I have noticed that it seems that the battery is lasting longer without the card installed.
Yet another reason to get that MacBook Pro.