Having an LLC opposed to a Sole proprietorship protects your personal assets.. as in if you get sued, you don't have to sell your car or home or have them possessed. With a SP, YOU are fair game if stuff goes wrong.
That's not to say that a SP is a bad move either, it just depends on what you are doing and what steps you are taking to ensure you minimize legal action against you (Service agreements, TOS).
I have a disclaimer that states that I do not warrant or protect customer data, everything should be backed up prior to having service performed. I also state that I shall not be held responsible for production loss, income loss, or charges incurred by the client while the computer is being repaired, or after repair. Situations such as these are the clients responsibility to setup backup systems or computers in case of down-time.
I don't work with companies as much as I do residential clients..