I purchased a Tom Tom XL340S at Target on Black Friday, for Christmas. I am totally "stupid" when it comes to these things. The instructions were not very detailed. I have read some places that say, do not hook them up to a computer and update, just use it out of the box. Updating with a computer can mess it up -- and if you do update it, make sure to make a back-up copy. Exactly what are they saying? Do I need to hook it up to my computer (let me add that I have dial-up)? If I need to do that, how do I make a "back-up" copy, and what is the purpose of it? Thanks for any clarifcation!