It is now possible to modify the drivers for the Nintendo USB wireless adapter to support nearly any Ralink chipset based wireless adapter. Many adapters will work including certain models from
ASUS Belkin Buffalo Cnet Conceptronic D-Link Gigabyte Linksys MSI
Here is a sample list http://damien.bergamini.free.fr/ral/list.html
You can find some of the drivers pre modified but if you are certain the adapter is Ralink based then go ahead and modify the files yourself. The only modification needed is to change the PCI ID listed in 6 of the files.
... Is it okay to link to other forums? Or should I try to explain the procedure myself?