Ok, before i start i am not a developer and what i am looking for more than anything is to know if what i want is possible.

I want to know if there is a way to track the referring/original url for paypal payments.

We are working with a company with a huge user base, they are advertising a product that is payed for through paypal on our site. We need to know which users sign up coming from their site and which ones came in direct.

Ideally i only want to track once the payment is made.

Any advice would be greatly appreciated.

I am assuming this is Payments Standard.

If this is, you will need to pass that information as a CUSTOM value in your HTML form 9or via the custom button system). This value will be passed back to you via IPN.