1.
GIMP - pretty good alternative, the Windows version requires Windows 2000 SP4, Windows XP SP2 or newer to run and it can be downloaded from
here, the official GIMP web site is
gimp.org.
GIMP features (
full list):
Photo Enhancement
Digital Retouching
Hardware Support
Supports various platforms:
* GNU/Linux (i386, PPC)
* Microsoft Windows (XP, Vista)
* Mac OS X
* Sun OpenSolaris
* FreeBSD
2.
Pixel image editor - paid alternative which runs on Windows, Linux, Linspire, MacOSX, BeOS, Zeta, QNX, MorphOS, FreeBSD, eComStation, OS/2, SkyOS.
Pixel image editor features.
3. More -
free image editors.