Gimp Editor – One of the most powerful general-purpose image editors around, very capable and often compared to Photoshop. It does, however, come with a rather idiosyncratic user interface and some quirks which less experienced users may find difficult to overcome. I would suggest those not so experienced take a look at the other products in this category. (XP/Vista 32/64bit)
GIMPshop – Is basically GIMP with a revamped GUI. Although it will not support Photoshop plug-ins (as GIMP does), it is much easier to use and less quirky. This from the website: “GIMPshop is a modification of the free/open source GIMP program, intended to replicate the feel of Adobe Photoshop. Its primary purpose is to make users of Photoshop feel comfortable using GIMP. It shares all GIMP's advantages, including the long feature list and customizability, while addressing some common criticisms regarding GIMP's interface: GIMPshop modifies the menu structure to closely match Photoshop's, adjusts the program's terminology to match Adobe's, and, uses a plugin called 'Deweirdifier' to combine the application's numerous windows in a similar manner to the MDI system used by most Windows graphics packages. While GIMPshop does not support Photoshop plugins, all GIMP's own plugins, filters, brushes, etc. remain available.” (XP/Vista 32/64bit)
Paint.net Editor - Not as capable as GIMP, but not as complicated either. Paint.NET is free image and photo editing software for computers that run Windows. It features an intuitive and innovative user interface with support for layers, unlimited undo, special effects, and a wide variety of useful and powerful tools. An active and growing online community provides friendly help, tutorials, and plugins. (XP/Vista 32/64bit)
Serif PhotoPlus 6 – Installs easily and is packed with features, including layer support. It looks and feels very much like a cut down version of Adobe PhotoShop. This is one where the publishers offer older versions of their commercial product as freeware. This may not be the latest version of PhotoPlus but it is still very good. NOTE: Email address registration required. (XP/Vista)
PhotoFiltre - Is the ‘new kid on the block’, available in a number of languages, including English, and is a relatively small (1.6MB) download. Like PhotoPlus, it looks and acts very much like an old version of PhotoShop. It can read and save files to JPEG, GIF, BMP, TIFF, PNG, RLE. Although it cannot handle layers and despite it’s lack if size, it comes with an impressive range of tools, brushes and filters and has a lot of functionality packed into such a small program. (XP/Vista)