Domain account trusted connection?

[Guest]

We are changing from using SQL accounts in our connection string to use NT
domain accounts. I have found some coe which I am using successfully on my
local machine, because the installed account ie; MachineName\ASPNET is what I
use in my VS2005 environment and this works great connecting locally to my
local SQL Server DB, since it is one of the accounts that I have locally as a
user in SQL Server.

The problem is when I try to connect to another remote SQL server (a test
server), it tries to use this same account (MachineName\ASPNET), and it can't
because it is not on the remote SQL Server box as an assigned user in SQL
Server for that Database. I don't want to use my machine name account ie;
MachineName\ASPNET, but I would like to use a domain account ie;
DomainAccount\ASPNET and I know I need to put this account on my local
machine and also add it to SQL Server and assign it to the database that I
want to connect to. My question is, where do I specify the name of this
domain account? Does it go in the web config file, or do I specify it in the
connection string, or is it specified as an impersonation in the web config
file? I'm assuming it would be in the web config using impersonation. I've
never used this. How do I do this? Here is my connection string:

<!--<add key="cnx_db" value="Server=XXXXXXXXXXX;Integrated
Security=True;Database=XXXPortal;Persist Security Info=True" />-->