IrfanView : The best graphics viewer in existence. Also comes with basic editing features, plugin capabilities and audio and video capabilities.
DotColor : Provides RGB and HEX color codes for anything you can see on your monitor.
//Context Viewer: Image preview in the context (right click) menu in Explorer file manager. This is a direct download from some of my other webspace This is currently unavaible from my other webspace because AOL shut down all their "member" hosted webspace. The original site is in Japanese. I am not sure if it works in WinXP, but it was a nice feature in Win98.
?> The GIMP : Recommended by Pistos, a GeoShell user, who said, "The best free alternative to PhotoShop, Corel Draw, Paint Shop Pro, etc."
MWSnap : Recommended by Pistos, a GeoShell user, who said, "A good screen capture utility. You can marquee sub-sections of the screen to capture."
Paint.NET : I've been using this at work. It's a basic graphics editor that is not as complete as The GIMP or Photoshop, but has more functionality that Irfanview. I use it when I need to make changes to images (or create them from scratch) and still use Irfanview for just viewing images.