This program is a real must have if your looking for more then just MS Paint that comes with Windows!
I think most of you already know it, specially for those who don’t:

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.

Features:

• Simple and intuitive tab-based multi-document user interface
• Now available in 8 languages: English, Chinese (Simplified), French, German, Japanese, Korean, Portuguese (Brazil), and Spanish
• Interactive Gradient Tool that makes it very easy to draw and then fine-tune placement and coloring of a gradient.
• User-definable color palette (as opposed to just the color wheel)
• New effects: Clouds, Median, Unfocus, Outline, and an improved Sharpen
• More intuitive and more powerful toolbar
• Generally improved and cleaner user interface
• History files are now compressed to save disk space, reduce disk activity, and improve performance.
• “Merge Down” layer command

Minimum requirements:
Operating system Windows XP (SP2 or later), Vista,Server 2003 (SP1 or later), Home Server, Server 2008
Processor 500 MHz or higher
RAM 256 MB (Recommended: 512 MB or more)
Free hard drive space 200 MB
Software Component .NET Framework 2.0
Graphics 1024 x 768 screen resolution

Download: