Strange Error When Connecting To Database.

 Hello,

I'm tyring a simple piece of code to conenct to my database: SqlConnection con = new SqlConnection("Data Source=localhost; Initial Catalog=OrderingSystem; Integrated Security=SSPI");
try
{
// Try to open the connection.
con.Open();
label1.Text = "&lt;b>Server Version:</b> " + con.ServerVersion;
label1.Text += "&lt;br /><b>Connection Is:</b> " + con.State.ToString();
}
catch (Exception err)
{
// Handle an error by displaying the information.
label1.Text = "Error reading the database. " + err.Message;
}
finally
{
// Either way, make sure the connection is properly closed.
// Even if the connection wasn't opened successfully,
// calling Close() won't cause an error.
con.Close();
label1.Text += "&lt;br /><b>Now Connection Is:</b> " +
con.State.ToString();
}

When I try this, I get an error:
"Error reading the database. Cannot open database "OrderingSystem" requested by the login. The login failed. Login failed for user 'NT AUTHORITYNETWORK SERVICE'."

The strange thing is, this code works perfectly If I use it in a Windows Forms application.

Is it a problem with SQL server, IIS or my code?
I'm using SQL Server 2005 (SP2) 32bit developer edition + IIS 6.0 + Visual Studio 2008 Pro all runnign on my Windows XP x64 PC.

Thankyou