Not too sure of the program is the shopping cart program or the Paypal program?
For the shopping cart, if you are looking for ASP, check out
http://www.spidersales.com or
www.vpasp.com. For PHP, check out
www.oscommerce.com. If you do want ASP, I have a smaller version of an ASP shopping cart that I can send to you.
If you are processing over $1,000 a month, you might consider a merchant account. Otherwise, check out
www.mypaysystems.com as well.