If I change some of the code in this to make it so site visitors can purchase multiple e-products at a time by adding them to the cart, rather than "Buy Now":

Change this:
<form name="_xclick" action="https://www.paypal.com/cgi-bin/webscr"
method="post" target='_blank'>
<input type="hidden" name="cmd" value="_xclick">

To this:
<form target="paypal" action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_cart">
<input type="hidden" name="add" value="1">

And also change the button gif to the cart button...

When Paypal sends it's notification to the ipn.php page, will the system send out the multiple files, or is it only capable of sending one file at a time?

Thanks!

>If I change some of the code in this to make it so site visitors can purchase multiple e-products at a time by adding them to the cart, rather than "Buy Now"

Sorry, they can't. The script isn't designed for multiple items.