R.J.
We went from leapster to an actual computer (hand me down, yay free... and HE didn't care it was a hand me down).
There are SO many amazing things online and for CDR drives
www.pbskids.org
http://kids.nationalgeographic.com/kids/
http://www.bbc.co.uk/schools/primaryhistory/
http://kids.discovery.com/
http://www.discoveryeducation.com/
http://www.gutenberg.org/wiki/Main_Page
Plus hundreds and hundreds of others... heck, even the CIA has a kid's page.
Then in CDR games you've got iSpy, Reader Rabbit, Clue Finders, Carmen San Diego... the list goes on and on.
Plus you can stream netflix or play dvd's on the computers as well.
If you don't have a hand me down option, refurb laptops can run as little as $100 each.