I have the $30 install disc and a MacBook Tiger full of problems. The Apple guy at Best Buy said that upgrading to Snow Leopard would help my computer a lot. How do I go directly from Tiger to SL? Do I need to back up all my stuff first? (I have an external USB hard drive.) If you give me any suggestions, could you please also give me instructions on how to do it? I'm a bit of a noob. Thanks a lot.