Knowing Sony as I do, I would strongly advise that you remove ALL sensitive data from the laptop prior to sending it away.
If you can access your CD or DVD writer, make backups of all critical data so that you can restore it on return of the machine.
If you cannot access the drives to write a copy of your information, get hold of an external USB HDD and copy them there.
Your other (more expensive but worth the money) option is to download and install Acronis True Image 11, and make a full backup image of your laptops contents. DON'T send it away with your details on it whatever you do!