setup IIs to use windows authentication for database connection

Hi,

    I have designed an ASP.net 4.0 application and I need to be able to configure IIS so that the person connecting to the application is also able to create a successfull connection to the database using his logged in windows credentials.

I am using IIS7, my database is MS SQl server 2008.

My databse connection string is =>Data Source=serverName\SQLSERVER;Initial Catalog=TESTDB; Integrated Security=true;

I cannot afford to change the database string and add a username password to it neither can I configure the app pool identity to a specific user.

Thanks in advance

Regards

Shirzad