I've had a macbook for about 4-5 years and have never thought about updating the OS, until now. I see that there have been a few updates since then . And I started wondering if it is a good idea to upgrade my 10.5.8 macbook (2ghz intel core 2 duo) to Snow Leopard and Lion. Are there any risks, is there any need to do this besides being able to get some software that won't work on the old system, etc. In short; should I?