The cost of encryption?

I am a MacBook Pro user (More on that later next week) and an insane backup junkie, but as far as protection of my data it comes to a tight grip on my bag and the ability to scream *really* loud.
With all the sensitive information resides on my laptop, which never leaves my side, I feel stupid letting it sit on the drive unencrypted. So what to do? I have read many articles that both praise and slam various forms of encryption. So, what do you do to protect your data? What do you use to encrypt? Why do you choose not to? Start the discussion!
