Reset Settings to Factory Defaults
Hmm I think my Powerbook's settings for networking and the likes are too messed up to fix. I can't send files through ichat and I can't access the pc desktop through the network anymore. Is there any way to reset every setting to factory defaults?
Without reinstalling the OS

Comments
You can play it safe and try simply moving certain pref files out of the folder, keeping them in a safe place in case you want to go back to your previous settings. Or go for the all-out-approach, and delete all the contents of the entire folder. Beware, though, as this may also delete registration files and the like that say that you really do own certain apps, and it will also get rid of prefs for apps like Words and Appleworks too.