Need a script to serve up content relevent to the referring webpage

I have an ecommerce website with lots of different products.

On my order form is a generic paragraph of text, I want this text to automatically change according to the webpage that referred them to the order form page.

So, or example if the visitor arrived from my;

/yellow-widgets.htm page the order form page would automatically display a paragraph of text about yellow widgets
/red-widgets.htm page the order form page would automatically display a paragraph of text about red widgets

or if they arrived from any webpage within my /left-handed-widgets/ directory folder the order form page would automatically display a paragraph of text about left handed widgets
etc, etc, etc.

Does anyone know of any scripts (preferably free! ) that would allow me to do this?

Thanks

 

use google for "landing page" =)