I post this in case anyone else runs across the same issue. Though, based on recent traffic, those most likely to need this wouldn't search hard enough to find it, so it may be a moot point. But we'll see.

Laptop:
Toshiba Satellite U305-S5077
Internal Wireless card: Atheros AR5007EG
External usb wireless card: ALFA AWUS036H 500mW

When I got the external one in the mail, plugged it in while I had BT running, and it came up on wlan1, as I already had my atheros card working on wlan0. Today, I plugged in the alfa device before bt booted, and I was looking for it on wlan1 as usual, except that ifconfig -a didn't show it, and ifconfig wlan1 up reported no such device. I unplugged it and plugged it back in, but still no wlan1. After a couple of minutes of head scratching, I took a closer look at the mac reported for wlan0 in ifconfig -a, and realized that it was my external alfa device.

It seems that by having it plugged in during boot, alfa grabbed the wlan0 spot, and ndiswrapper wasn't smart enough to move to wlan1 (maybe that's in a config file somewhere. I don't know, and I haven't searched for it yet ). So I unplugged the alfa, issued a rmmod ndiswrapper followed by a modprobe ndiswrapper, and then plugged in the alfa. An ifconfig -a revealed both cards, so all is well. Now I know, and knowing is half the battle.

Incidentally, I am using ndiswrapper for my internal card because the madwifi drivers don't currently support the AR5007EG. I have another thread on that out there, if anyone is interested.