I ended up going with a D-Link DWL-G510. I have it working under ndiswrapper and it seems to be fine. It is syncing fine with the LinkSys AP in the basement. Guess I will get another one of these cards fro my other desktop. Thanks for the suggestion.
The ndiswrapper solution is interesting, but if you're curious at all, the madwifi drivers seem to work perfectly well, and support WPA, etc. I would imagine its possible that in the future they could support newer versions of the 802.11 spec, given that you dont need a change in the radio.
The madwifi docs suggest that both the g510 and 520 are compatible; D Link suggests that the 520 can get "up to 108 Mbps!!elevens!" and that it can do WPA (slightly more important). Newegg claimed the 510 didnt do WPA (it seems it does) so that's why I wound up paying ten bucks extra for nothing, it seems. Anyways, just a thought that you or anyone else following along might check it out, especially if you're considering AMD64.
Justin