I think i found something interesting:
Free and Open Source
Download: http://www.getpaint.net/redirect/mirror ... anews.html
Just requires de .NET Framework 2.0
Just download the Setup, install on any folder and run on any computer.
Paint.NET is image and photo manipulation software designed to be used on computers that run Windows 2000, XP, Vista, or Server 2003. It supports layers, unlimited undo, special effects, and a wide variety of useful and powerful tools.
It started development at Washington State University as an undergraduate senior design project mentored by Microsoft, and is currently being maintained by some of the alumni that originally worked on it. Originally intended as a free replacement for the MS Paint software that comes with Windows, it has grown into a powerful yet simple tool for photo and image editing. The programming language used to create Paint.NET is C#, with a small amount of C++ for setup and shell-integration related functionality.
Simple, intuitive user interface
Every feature and user interface element was designed to be immediately intuitive and quickly learnable without assistance. It is also designed to be immediately familiar to users of the original MS Paint software that comes with Windows.
Usually only found on expensive or complicated professional software, layers form the basis for a rich image composition experience. You may think of them as a stack of transparency slides that, when viewed together at the same time, form one image.
Paint.NET includes simple tools for drawing shapes, including an easy-to-user curve tool for drawing simple splines or Bezier curves. The facilities for creating and working with selections is powerful, yet still simple enough to be picked up quickly. Other powerful tools include the Magic Wand for selecting regions of similar color, and the Clone Stamp for copying or erasing portions of an image. There is also a simple text editor, a tool for zooming, and a Recolor tool.
Everybody makes mistakes, and everybody changes their mind. To accommodate this, every action you perform on an image is recorded in the History window and may be undone. Once you've undone an action, you can also redo it. The length of the history is only limited by available disk space.
Many special effects are including for perfecting your images. Everything from blurring, sharpening, red-eye removal, distortion, and embossing are included. Also included is our unique 3D Rotate/Zoom effect that makes it very easy to add perspective and tilting.
Adjustments are also included which help you tweak an image's brightness, contrast, hue, saturation, and levels.
Open Source and Free
Paint.NET is provided free-of-charge, and the source code (all 105,000 lines of it) is also available for free under generous licensing terms. The bulk of Paint.NET is written in C#, with only a small amount of code related to setup and shell-integration written in C++.