Our six-year-old son has moderate to severe CAPD and a language processing disorder. He attends language therapy and enjoys it very much. I think he knows there is something different about him. His twin brother does not have any learning disabilities.
How much should I tell him about his LD? What should I tell him? He's a very smart boy with an IQ of 116, but has a very difficult time understanding spoken language. He learns better by doing hands-on projects and working at the computer.
There's an excellent book by Dr. Mel Levine called All Kinds of Minds
that uses brief stories about individual kids to explain how everyone's mind is different. I have found it very useful to use with kids. There's also an audiotape available of Dr. Levine reading the book.
I don't know of any computer program or non-verbal presentation of learning disabilities that would be appropriate for a young child.