I'm glad you like it. I love it when freeware and OS X combine so elegantly. The other screen savers work the same, but Cosmos just seems cooler to me than the others. BTW, you can add your own shots to the Cosmos screen saver by right-clicking on /System/Library/Screen Savers/Cosmos.slideSaver and selecting Show Package Contents, then opening Contents/Resources and dropping new pics there (you'll need an admin password).