Check the manufacturer's web sites to see if their usb-wireless adapters have OS X drivers. If they don't, they probably won't work. I think MacSense might have one that works.
Another alternative, which is slightly more expensive, but a whole lot more flexible is a wireless-to-ethernet bridge. These require NO drivers, and once configured, you can plug any ethernet device into them just as if they were a hub. (In fact you can uplink them to a hub and connect more than one wired device to your wireless lan at once, subject to bandwidth sharing.)
Linksys makes two of these devices, the WET11 and the WET54G, the former being 802.11b and the latter 802.11g. D-Link makes similar devices.
I have a WET-11 which works just great with my daughter's Rev. B iMac, and the beauty of it is that I can also use it to connect any other computers I or a friend brings home without installing drivers or configuring.
The only disadvantage is that it is TCP/IP only. I.e., it does not support classic AppleTalk. This is of no significance unless you are using system software prior to OS 9 or need to share an appletalk printer.
By the way, many if not most of the USB to wireless adapters likewise do not support Appletalk.