Windows Live Photo Gallery is a photo sharing and photo editing application which is why you can't find it. You must have set Photo Gallery as your default application to view photos. I can't remember for sure how to do this, but if you right click on a photo in the Photo Gallery, can you select Open With and then select the Windows Photo Viewer and then set it to "always use this program to open these types of files?"
Fireplace, yarn, knitting needles, books, wine... check. Yup, I'm ready for winter.