I have the wired adapter, but the trouble is the Wii and the wireless router are in different rooms with a three foot wall between them.

I realize that a wireless router might be an answer but the the Mac works fine as an ethernet bridge when it's set up right.

With some setups I can surf the net on the Wii but not play an online game so it's either a DNS or a firewall issue and the IP addresses boxes on the Wii are as follows:

000.000.000.000

so when you enter 192.168.2.1 save it and check back on what you've entered it appears as 192.168.002.001 and I'm not sure if it should be 192.168.200.100 instead?