Web Page in Portal Page

I have added the Web Page component to a portal page and using a direct call works fine.  I however need to be able to change the URL based on the value(s) from another form also on the page.  Basically I've created a sharepoint site with sub directories matching the requisition number.  I want to take people directly to sub folder but in order to do that I have to embedd the requisition number within the URL.
Anybody have any ideas on how to do this?

Thanks
Robert