Access Hidden Themes in Windows 7

To add to Pete’s post:

If you examine the five country Wallpaper folders you will notice that only the US and GB have unique pictures, the other three are identical (lazy Microsoft).

However, I thought I’d be clever and copy the pictures that I like in the other folders to my (GB) folder thereby giving me more pictures in the wallpaper slide show. I edited the .theme file (took ownership first) to include the new pictures, changed ownership back to the Trusted Installer, clicked on it and, voila, Notepad opened, i.e. it wasn’t added to the Personalize applet. I know I changed ownership/permissions properly but I, obviously, don’t know enough about the intricacies of the Trusted Installer.

The simple answer, which I’ve now adopted, is to create a folder, then copy (not move) in the pictures you want, go to Personalize and Browse to your new folder and set up the slide show delay, etc.