Creating sequentially numbered form using Word 2007

Currently we have rental forms that get filled out everytime one of our rental vehicles gets rented. In the past these forms have come pre-numbered from a local printing company. To save the company money, I was going to re-create the form in Word so that we didn't have to order them. Also, this way the form will look much tidier as the information will not have to be handwritten in. The only problem is, how do I add a sequential number to the top of the form. I need the first form to be say 03101, and then everytime the form is opened and saved thereafter, I need it to sequentially go up in numbers.
If this is even possible, I would only like it to give it the next number if the form is actually saved, not just opened, as sometimes the form will be opened, but not saved, and in that case I don't want it to get the next number.
Unfortunately, I am an amateur when it comes to VBA code. Could someone show me how to write this code, and how to put it into the document.?

Any help would be much appreciated

Alanda

This may help you...

Using Sequential Document Serial Numbers