Teredo?
 

Found an entry for this in my router's virtual servers table, I guess Vista must have placed it there?

According to this it's a feature of Vista that poses a possible security risk.

Question is, do I really need it or can I remove it, and if I do remove it how do I stop Vista reinstating it?

[Edit]

This says it's OK to disable it & gives several ways to go about it...

Re: Teredo?
 

Well Symantec have made a report regarding the security implications of Terado HERE 4th one down

If you are on a Virgin connection then you only connect using IPv4 not IPv6 which it is meant to access.