Changing the Hosts or Lmhosts files in Vista
Many power users are used to making changes in their Hosts and/or Lmhosts files that are used for name resolution, especially when they travel with their laptops. In Vista, you may find that trying to change these files results in an error message even though you're logged on as an administrator. The key is to run the Notepad program you're using to edit the file in administrative mode. You'll find instructions in KB article 923947 at:
http://support.microsoft.com/kb/923947/en-us