Windows Photo Gallery is my default for all images because it's the quickest, simplest image viewer I've seen. There's only one problem... I tend to do a decent amount of graphics for applications I write, which don't usually have the same background color Photo Gallery does. Beyond that, transparent photos are displayed with a white background. I wish I could change the background color of Photo Gallery and see how transparency is used within the photos. While I want this for seeing how an image looks in different background colors, it's also nice to see images on a black background. Typically, if you're looking at photos or a movie, you have a black background to bring more focus to the color of the picture. Could you imagine watching a widescreen movie with a white background? I have a feeling it would be hard to do.