I would personally recommend ubuntu. It's also free and unlikely to get viruses. Plus, In my experience from helping the elderly and other computer illiterates get connected, it often has a much gentler learning curve.The main hurdle then would be to find the cheap hardware with decent compatibility (perhaps a cheap 2 in 1).

Also, you should consider approaching canonical about sponsorship. Considering their relationship with amazon there has to be some funding to be found there.