If you use the Windows Picture and Fax viewer to preview images, but would like ro use a more sophisticated image editor than MSPAINT, here is a tweak to change the default editor:

Open your registry and find the key :
[HKEY_CLASSES_ROOT\SystemFileAssociations\image\shell\edit\command]

Modify the (Default) value to the full path of your favorite editor.

Note: The string of the path name should INCLUDE the quotes and the %1 argument. For example:

"C:\Program Files\Adobe\Adobe Fireworks CS4\fireworks.exe" "%1"

The default entry for this value is:

"%systemroot%\system32\mspaint.exe" "%1"