Here is GIMPshop based on GIMP, Gnu Image Processor, sort of the free version of Photoshop. I have used GIMP in the past but my complaint has always been that it just does not look like Photoshop. Well, now it does. If you scroll down and get the 8mb GIMPshop for Windows you will have a free software package that is every bit as powerful as Photoshop but costs $0 instead of the $600 or so the PS costs. Get it. It is GREAT.
Get the download for WindowsXP here and read about Gimpshop and its various distros and view some screenshot comparisons here at http://www.plasticbugs.com . The various elements of GIMP have simply been rearranged to agree as closely with Photoshop as possible.
Update: The plasticbugs.com site seems to have been swamped. You can get the windows install for Gimpshop here at http://blog.yumdap.net/archives/20-GIMPshop-for-Windows.html