Yes, go to www.GAMESTOP.com and you can buy the ethernet adapter.
here is the link:
Okay so I finally got my Wii and I am happy that I was finally able to get one. But I don't have a wireless setup. I don't really want to go out and buy a wireless router just for my Wii. My computer doesn't have windows xp so I can't get the Nintendo thing. So I was wondering if there are any USB-ethernet attachments were I could just just plug a usb connector into the wii that has a ethernet attachment and plug in my internet connection? I asked at Walmart but they didn't have anything. I would be greatful for any help, thanks in advance.