How can I configure NT to display a thumbnail of bitmaps as the icon instead of the Paint icon?

A. A. Perform the following, for best effect make explorer use large icons

1. Start the registry editor (regedit.exe)
2. Move to HKEY_CLASSES_ROOT\Paint.Picture\DefaultIcon
3. Double click on Default in the left hand pane, and change to %1, click OK
4. Close the registry editor. The change will take immediate effect.