One of the niggling points of getting ready for IP6 is that on some Windows 7 installations (but not all) the local loopback address gets returned as :::1 instead of 127.0.0.1.
The :::1 is a valid IP6 address and can be returned even if still using IP4 addressing. The fix for it involves editing the hosts file. On a Windows 7 box this is located in two places but the one to edit is the one in C:\Windows\System32\drivers\etc
To edit this file you need to run Notepad as an administrator. The easiest way to do this, I found was to use the option 2 technique at http://www.sevenforums.com/tutorials/157432-hosts-file-create-edit-hosts-file-shortcut.html