I've never reinstalled my 3 year old Leopard since I bought but now its the time Questions: 1. Should I upgrade to Snow Leopard ? The only reason for that is for some compatibility issues, as Leopard may be quite old for some new programs (or upgraded programs) to be compatible with , and Lion is too young and possible more restrictive (requires app store to download etc) . I would still install Leopard but need an idea if I'm doing wrong ? 2. As I started living in away from home I was wondering if using FileVault would be any useful, in case of lost or stolen, the data being more important than the value of the macbook. The drawback of using FileVault is that it may slow down some apps (i need to research on that) but on the other hand I am able to keep the sensitive files encrypted without using FV and thats what I'm thinking doing.