I had a 2006 Macbook just give up the ghost - but it was used (and abused) daily. I have a 2008 Macbook that I just upgraded to an SDD, a new battery, and maxed out it's memory for my daughter in a similar effort to what you're wanting to do for your son. I've already gotten 1 year out of it since doing the upgrades and I'm expecting to get at least 2 more. All told you can expect to get roughly 10 years out of a Macbook.