can't use the laptop keyboard and such because it is too small/inconvenient for his hands.
If the laptop isn't working for him - how about selling it?
Maybe get one that he likes better?
Or you could just get a replacement desktop tower for a few hundred bucks to carry out your objective. Lenovo IdeaCentre H420 (77525GU) Desktop PC $380
Pentium G630 2.70GHz (Sandy Bridge dual core) CPU, 4GB RAM 500GB HDD