Screen Scraping & post through two urls in .NET

Does anyone know how to use the post method to get through two urls so i can screen scrape information from the second url?

ie - i need to post some values to get to the first url. Then to go to the second url i need to post a second set of values. It's the second url where i need to screen scrape information from.
(Note i have to go through the first url in order to get to the second one)

I can get it going in VB6 but not .NET. In .NET is seems like the webclient session closes down after my first post attempt therefore preventing me getting to the second url.

If anyone has any code or knows how to post and screen scrape through 2 linked URLS then please let me know.
Any advice or help would be much appreciated as I haven't had much joy finding a solution to this in the past few days.