i've bought an original "Nintendo USB to Ethernet lan adapter", only 29 € shipped to my home from Republic of San Marino (http://www.hardstore.com/default.asp?cmd=getProd&cmdID=8287) (i'm italian).

You can observe in the comments that this product use the ASIX AX88772 chip (100 Mbit / USB 2.0)

When it will arrive i'll try and send you a feedback so you can update the page about the supported devices (http://wiki.wdtv.org/doku.php?id=supported_usb_devices).

This device is avaiable in a lot of game shop and fom the joy of italian users, it's few click away from you ordering online (you can pay with paypal, or credit card or trough cash to "bartolini express" at your home).

If really you dont' need a Gigabit adapter this is the best chioce (certainly, if it will works on wdtv)