I don't have another card, and since they run about $150-200, I'm not keen on buying one just on a hunch, especially since this one seems to work in other machines.

I'm getting the Sierra Wireless drivers you mentioned now, though I'm pretty sure they're already installed, it can't hurt. I'll check the Event Log too, hadn't thought of that.

Nihil: I've tried booting to a clean install of WinXP pro, installing the drivers, and then rebooting with the card plugged in, and it freezes on that cute XP splash screen you get on startup.