Mikey has an old 20080 Core 2 Duo MacBook Pro, and he wants to upgrade the hard drive in it. He wants to know if any 2.5" hard drive will work, and if he can install Snow Leopard on it.
Leo recommends going to MacSales.com to get the hard drive. They're Mac specific and if they say it'll work, it will. While Mikey is at it, he may want to consider an SSD (solid state drive) instead. That would make it a lot faster. Leo says to go to Mountain Lion instead of Snow Leopard if he can. If a program prefers Snow Leopard, he can always upgrade to Mountain Lion once that program supports it. Apple still sells Snow Leopard for $19.99. He'll have to purchase iLife though, since that only comes free with new Macs.