I just discoverd the first (and only?) advantage of Windows Vista: Vista has IPv6 enabled by default, via Teredo. Only IPv6 resolving seems disabled, probably to avoid unmeant IPv6 usage. ;-)
Anyway: with Firefox on Vista I'm able to visit http://[2001:4860:0:1001::68]/ and search. Cool!
(http://[2001:4860:0:1001::68]/ is the litteral IPv6 name for http://ipv6.google.com/)
Please note: Maybe you have to copy-paste the http://[2001:4860:0:1001::68]/ by hand.
Oh wait: Microsoft says "Yes (the Teredo component is enabled but might be active or inactive, depending on the computer's configuration)", so YMMV. Please post results in the comments: can you visit http://[2001:4860:0:1001::68]/ from your Vista machine?
You can also try http://[2001:610:510:0:192:42:113:60]/ (which is the litteral name for http://www.ipv6.surfnet.nl/) and look at the right lower corner to find out your own IPv6 address: "You are accessing this server over IPv6 from 2001:0:d5c7:a2ca:302a:c6....".