My son has enjoyed this free online tutorial (designed for 7-11 yr olds). Typing really does help when they're struggling to get out ideas and the handwriting is still sloooow, although thankfully that too has improved a lot this year.

Lori, this might be too rudimentary for your ds, but I figured it might help someone who's just starting...

http://www.bbc.co.uk/schools/typing/