Addendum to the previous mail about Teredo on XP and Vista: go6.net still shows an IPv4 address when forcing v6 traffic through Teredo on Vista. It looks like Vista prefers v4 over v6 still when Teredo is being used. For the test, that'd mean that v4.p* and v46.p* will load over v4, while v6.p* will load over v6, if Vista has been forced to use Teredo.