GIMP INSTALLATION

GIMP

The open source alternative to Photoshop. Doesn't have all the bells and whistles but adequate for most tasks.

http://www.gimp.org/

(To force GIMP to use a single window, Windows > Single-Window Mode)

GIMPShop

GIMP configured to look like Photoshop. Not always the latest version of GIMP. Has a Apple Mac version.

http://gimpshop.com/