HTTP_Clients and Files - Part 2

Okay, I got HTTP_Client to work with files no problem (on some forms) however, the forms that use a session in the qurey string is causing me problems. Here is one scenario: 1. HTTP_Client posts my username and password info to a login page. 2. I am then redirected to a page that now presents me with a session id in the query string. 3. When I click on the submit button to download the file, i need to pass the session id as a hidden variable to the form. How can I get a variable from the query string from one post() response and then send it to my next post()? Anyone have any experience with this? Thanks Andrew