not sure if this is relevant, but the preferences.xml file is stored in the directory C:\Documents and Settings\username\Application Data\Inkscape\, which is normally a hidden directory.
so even if you delete the entire Inkscape installation directory, the preferences file will not be deleted. If you delete it yourself or rename it, then a new default file will be created for you next time.
not sure if this is relevant, but the preferences.xml file is stored in the directory C:\Documents and Settings\ username\ Application Data\Inkscape\, which is normally a hidden directory.
so even if you delete the entire Inkscape installation directory, the preferences file will not be deleted. If you delete it yourself or rename it, then a new default file will be created for you next time.