MacTCP doesn't support DHCP. If you are using the defaults, then that's why you're not getting connected. Many people get fooled by MacTCP's option for "dynamic addressing," but it is manifestly not DHCP.

Btw, wannabe generally works fine under 7.1 if you install the drag and thread manager extensions. I say "generally" only because the author doesn't guarantee it. However, I've not run into an exception.