The usual default setting will just overwrite the files in your current System Folder.
One drawback to a clean install, though, is that your customized settings, extensions and preferences are still in your old System Folder.
You can either reinstall your modem, printer and other extension software or move the old files into the corresponding folders within your new System Folder.
Double-click on your Mac's hard drive icon and find the System Folder.
Netscape will create a new Preferences file if it doesn't find one in the System Folder.
System extensions were enhanced by being moved to their own subfolder; a subfolder in the System Folder was also created for the control panels.
Fonts were automatically installed when dropped on the System Folder, and became available to applications after they were restarted.
Prior to this, one would have to manually bless the copy of the System Folder that they wished to use.
Mac users will find the History file in System Folder: Preferences: History.
Put that file into the System Folder and restart the Mac.