Paint.NET is a powerful, light-weight, and free graphics editing program.  It requires that you have the .NET framework installed in a Windows environment in order to run.

If you aren't sure if you have the .NET framework installed on your computer, use the "Windows Update" or "Microsoft Update" utility, and check the Optional Updates section.  If you don't see the .NET Framework listed as an optional update, then it's probably already installed on your computer.  Otherwise, install it using the Windows/Microsoft update utility.

For you graphics designers, this is a bitmap or raster-based graphics program, not a vector-based program.  You won't be able to use it to replace Corel Draw.  It will give any any raster-based graphics program a good fight, though, including PhotoShop.  Yes, people have actually reported that they've replaced PhotoShop with Paint.NET

I'm not a graphics designer, so I can't really attest to the high end features that I've seen reported.  However, I've used it for basic functions to get stuff ready for the web including changing image size, file type, and compression, and it works easily and flawlessly.

I first learned about this utility by watching an interview with the program's creators at http://www.microsoft.com/.  It was developed by 3 Washington State Univerity students as a school project.  They've all since graduated and are in the working world now, but they are still adding improvements to this program.  To learn more about this utility, go to http://www.getpaint.net/.