I've always thought the Mac screensaver that scrolls through pictures ultra-smoothly was really cool and I wanted it for PC to display my astro pics. I took very long to find these and almost gave up but I finally found two:
Motion Picture Screensaver and
Nostalgic Screensaver
Use them to slideshow your own astro pics or pics from APOD and NASA.
ENJOY!
Remember to check out these pictures from:
Vision Afar
Astronomy Picture of the Day
NASA Image Galllery
Visible Earth, pictures of Earth from space.