I kind of like using Window Photo Gallery in Windows Vista. Its a nice way to display and browse my photos.
But recently I moved my photo collection and Photo Gallery “lost” most the photos.
There didn’t appear to a way to delete a photo from the gallery without deleting it from the disk as well.
After some searching I found that what you have to do is delete or rename the file
C:\Users\[username]\AppData\Local\Microsoft Windows Photo Gallery\Pictures.pd4
via deleting photos in windows photo gallery – Vista Forums.