GIMP - the GNU Image Manipulation Program - runs fine on Windows.
Homepage: http://gimp.org/windows/
Download: http://gimp-win.sourceforge.net/stable.html
You need to install the GTK+ 2 Runtime Environment first (from the same download page).
Then install GIMP as any other Windows program.
That's it! You're now ready to manipulate any kind of images.
Last modified: Wed Jan 17 14:57:48 Romance Standard Time 2007