Replace "Paint" as default program for 'Edit' Explorer command
I found this worked flawlessly in changing what Edit did, and you can choose any program you want.
Open up the registry editor: Start →
regedit
Navigate to
HKEY_CLASSES_ROOT\SystemFileAssociations\image\shell\edit\command
On the right-hand side double-click on
Default
and change the value to"C:\YOUR_PATH_HERE\APPLICATION.exe" "%1"
This has the advantage of changing it for all files that Windows 7 considers an image.
Source: m-schmidt.eu