Computer was going a bit slow (in fact it was crashing all the time) because of fan problem mainly, I believe, but decided to upgrade ram whilst I was at it.
Very good. Fairly straight-forward; however, I had to attempt it twice as one of the ram sockets wasn't reading the first time. I switched 2 x 2GB ram for 2 x 4GB ram. Computer works very well now. It's running quicker and ram doesn't get overloaded unless I open too many tabs on safari, but I found a fix for that. I don't know if my computer is working better because of the ram upgrade or fan repair; I suspect it is because of both.
Follow the repair guide carefully and don't go all gung-ho.