I meant since I'm not using wireless networking, network-manager doesn't seem to be doing me any good anyway - just an icon in my notification tray taking up space. (That would be where I'd go to select a wireless network...)

I followed those instructions and got an interesting error:
$ sudo /etc/init.d/networking restart
* Reconfiguring network interfaces...
Ignoring unknown interface eth0=eth0.
Ignoring unknown interface eth0=eth0.