I just bought the WD TV Live HD Plus and the Airlink101 USB Wireless adapter. The setup could not find any networks, including my own router, and manually entering the IP address didn’t work either; in fact, although it accepted my manually entered IP address, when I tested the connection it said it was invalid.
WD Live HD Plus
Airlink 101 (AWLL5077)
Linksys router (WRT54G)
using PPPoE, WPA-1 personal security [tried disabling it also]