http://www.ambientdesign.com/artragedown.html
http://www.ambientdesign.com/artrage.html

ArtRage - Free Painting Software for Windows
ArtRage is a painting package designed to provide a realistic and fun simulation of using paint on a canvas, along with pens, pencils, crayons, and other tools. ArtRage is available for both Windows and Mac OS X. It can be used with a mouse, but works better if you have a graphics tablet, or even better on a Tablet PC where ArtRage takes advantage of the unique interaction of pen and screen to produce a realistic painting feel.
ArtRage is all about playing with paint without the mess, and having fun in the process. You can paint your own image from a blank canvas to completed work, or load in a picture to trace and have the tools pick their colours for you as you paint over it.
ArtRage is a cute little program for experimenting with digital art. As the developers say, you can play with paint without any of the mess or the expensive supplies. However, it definitely has some annoying quirks and bugs. The brushes lag behind your cursor, and don't respond well to pressure. Pressure sensitivity comes and goes, and when it does work it affects opacity only, and not the thickness of the stroke--unlike a normal paintbrush. As such, it doesn't feel as realistic as the home page might lead you to believe. Also, many of the strokes had a very unnatural quality to them. 
System Requirements
- Windows 2k/XP. Windows 95/98/Me should work but are unsupported.
- Macintosh OS X 10.2 or higher on a G4 or faster.
- ArtRage works with a mouse, but it works best with a graphics tablet or on a Tablet PC.