I have an old MacBook that I would like to donate, and first need to put a new HDD in it. The MacBook is white, plastic and from around 2007 or 2008. It had Snow Leopard on it. I used the original HDD for backups, and have since destroyed it. Are there any particular specifications I need to be aware of when I buy a new HDD for this so that it will work? I just want to buy a check HDD so I can install Snow Leopard and have a working computer to donate. Technology changes so quicly that I am afraid a new HDD might be too thick or not be compatible from a technical standpoint. Any ideas?