/Users/~/Library/Preferences/com.apple.NetworkUtility.plist
/Users/~/Library/Preferences/com.apple.internetconfig.plist
and several more with "internet" in them.
But it is easy enough to take screen shots of your setup in System Preferences >> Network and then reset them without dragging around old prefs.
Unless you are planning to erase & install, they will be preserved with the other 2 options.
-mj