My 1 year old uMBP's harddrive has failed me and now I have to get a new one. Which one should I get? Is 5400 rpm really that much different than 7200 rpm? Are there ones which are commonly known to have problems [loud drives] Seagate Momentus Western Digital Scorpio MOST IMPORTANT QUESTION - if I have my original Snow Leopard DVD, is that all I'll need? The screw drivers as well to take the harddrive out, put the new one in, and boot it up with the DVD?