The Windows 7 beta has a pack of hidden and locked themes. To unlock hidden themes do the following:
  • Step 1: Open the Explorer (Windows + E) and go to C:Windowswinsxs
  • Step 2: Enter *.theme into the search field. Alternately you can use the * sign on the number block.
  • Step 3: You’ll get the Click me prompt
  • Step 4: Double-click the themes ZA, US, GB, CA, AU to install them.