This year's Fine Arts Festival @Orme was awesome! We had several artists running classroom workshops for the students. You can checkout the school's event flyer on the event here. I was involved with assisting Kevn Lambson who teaches the Computer Art class at Orme during Fine Arts Festival Week. Kids used several programs including NewTek Lightwave 3D, Pixologic Zbrush, Corel Painter, and Adobe Photoshop.

You can check out Kevn Lambson's website at http://www.idearstudios.com

Here are a few useful links to find the demo versions of the programs listed above:

Lightwave 3D
http://www.newtek.com/lightwave/lwtrial.php

Zbrush
http://www.pixologic.com/zbrush/trial/

Corel Painter
http://www.corel.com/servlet/Satellite/us/en/Content/1152796555406

Adobe Photoshop (and other Adobe products)
http://www.adobe.com/downloads/

Also, Kevn reccomended some open-source (free) programs out there you can take advantage of if you're working in Linux or don't like the price tags on the above programs:

Unreal Development Kit
UDK is Unreal Engine 3 – the complete professional development framework. All the tools you need to create great games, advanced visualizations and detailed 3D simulations. The best tools in the industry are in your hands.
http://www.udk.com/

Blender 3D
Blender is the free open source 3D content creation suite, available for all major operating systems under the GNU General Public License.
http://www.Blender3D.org

The Gimp
GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring. It works on many operating systems, in many languages.
http://www.Gimp.org

InkScape
An Open Source vector graphics editor, with capabilities similar to Illustrator, CorelDraw, or Xara X, using the W3C standard Scalable Vector Graphics (SVG) file format.
http://www.inkscape.org