Welcome to the forum.
With Ps CS3, there will not be a replacement disc option. However, you can go to ProDesignTools, and download the "trial" for Ps CS3. Be very sure to follow the instructions 100%, or you will get "Access Denied." http://prodesigntools.com/tag/ddl/ Scroll down for Ps CS 3.
Then, when you have installed that trial, you can Activate it with your S/N.
After everything is up and running perfectly, just create a DVD-Data disc, with that trial installer, and also make note of the S/N on the container.
Good luck, and be sure to follow the ProDesignTools instructions 100%!