My 7 year old loves KidPix [and my 4 year old loves the sounds it makes!].  It is an amazing program that lets kids create "dynamic works of art using a variety of virtual media."  They even use it at school during computer class. Features of KidPix include: 

• Work with traditional art tools like chalk, paint, pencil & crayons
• Choose Crazy Art Tools to paint with the "electric mixer", spray paint and more!
• Sound Art! Paint wild pictures using the sound of your own voice!
• Spray your scene with 3D shapes, including bugs candy and more!
• Create your own animated movies
• Use special effects like warp, splash and smear

Try it out - it is great fun.  Your kids will love it.  Amazon usually has it for about $15 - and around the holidays, I found a rebate and got it virtually for free!