We've expended an enormous amount of energy keeping the kid from touchscreening our laptops, so we're already doomed on this one, but maybe it's not too late for you.
A dad named John loaded Firefox onto a surplus point-of-sale touchscreen and set it to open to the "surprisingly touchscreen friendly" PBSKids.org. Now his kids, 18-mos and 3-yo, have their own play station.
See more details at Make's blog. First, pick up an IBM Anyplace Kiosk ELO Touchscreen for cheap... Oh wait, they're like $500 on eBay...
DIY Kids Kiosk [makezine]
