Getting HTML from a page behind a login

Question

This question is a follow up to my previous question about getting the HTML from an ASPX page. I decided to try using the webclient object, but the problem is that I get the

Answer 1

Well does opening the page in a brower with "Login.aspx?UserName=&Password=" normaly work?
Some pages may not allow login using data provided in the url, and that it must be entered in the login form on the page and then submitted.