Norton Ghost 15.0 / Windows Vista / copy hard drive

I am hoping someone has the answer to my questions.  I have searched the boards and forum and am unable to get an answer.

I am on a laptop and want to upgrade my hard drive.  In order to do so I need to copy the hard drive to an external hard drive, take out the old hard drive, put in the new hard drive, then copy the hard drive back to the new hard drive.

MY QUESTION: Norton Ghost states that it will erase anything on the external hard drive when I request to copy of the hard drive.  Will it delete everything on my external hard drive?  I have photos and other stuff on it that I do not want to have erased.

Could someone suggest a solution if to do this type of hard drive copy.  I do not have a link to copy the hard drive I am using to the new hard drive. I only have the one computer.

Thank you.