I have USB 802.11g stick. I think it's a belkin. I died plugging that in, but couldn't figure out how to get it to work. If I simply remove the airport card, perhaps that work.
Well... I do not know how you died when plugging that in. The Belkin USB dongle is going to need separate drivers that are not included in OS X. If you report back with the model number, I may be able to help you find the drivers if they exist.