Integrated Authentication and change user

[Mino]

Hi!!
I develop an Intranet Web Application and I use the Integrated Authentication,
ASP.NET 2.0 and IIS 6.0, but I'd like to enable the function to change the
connected user (like Sharepoint)...
Which is the method to do this??

I use this code:

Response.Status = "401 Unauthorized"
Response.AddHeader("WWW-Authenticate", "NTLM")

to ask the user credential, but after the use insert the correct credential I
can't redirect to Home page...

Any Idea?
Thanks.
Mino