Hi everyone, I've recently bought a second hand macbook pro, i've recieved it today and im trying to update to OS X yosmite although my laptop is saying that my computer is up to date! now do i need to purchase the OS X Snow leopead and install it to then be eligiable to the free update?? pretty much everything i need to download isnt capitable with this old os x!! if you all could help me out that would be great!!! Thanks in advance!! Josh.