http://www.linuxuser.co.uk/reviews/gimp-2-8-review-who-needs-photoshop/ (http://www.linuxuser.co.uk/reviews/gimp-2-8-review-who-needs-photoshop/)
There's is a Windows version to, also open sauce which means it free to download and use.
I tried using Gimp during 2007. Found it very difficult so purchased CS5 and have not looked back.