Just get ArtRage - an easy-to-learn but very realistic painting software program that will let you draw paintings and sketches on the desktop just like any professional artist.
With ArtRage running, your computer screen becomes the drawing canvas while the mouse pointer turns into a brush or a felt pen.
You can paint with oils, sketch with pencils, sprinkle glitter, and more. Or paint with gold leaf, silver foil, and other metallic colors.
Artrage also has tracing tools to draw paintings based on any existing photographs or digital drawing similar to the Virtual Painter addon for Adobe Photoshop.
In other words, Artrage is like having the amazing features of Alias Sketchbook Pro or even Corel Painter for free. And you don't need a Tablet PC for using Artrage 2.2.
Artrage is available for Windows and Mac OS X as a Universal Binary. [Artrage Screenshot]
Ambient Design Artrage [Play with Paint] Download ArtRage 2