Query Exchange for unread email count

First thing, I am able to successfully query exchange and retrieve a user's unread email account if I have their user name and password. I pulled the code from a forum post and re-worked it slightly using VB.net and everything is working fine.

Here is the issue: We want to move to dual authentication for our Intranet (Forms & Windows) and I have a solution working, but the users are not required to provide their passwords anymore since we are automatically logging them in with their Windows account, provided they are logged into our network. So I am no longer able to pull their unread counts. If I try to use another account, the server returns authorization errors.

Here is the question: Is there a way to create some sort of account that is able to query any account on the Exchange server?

What are the drawbacks to creating such an account, if one exists?
Will this user have complete access to everyone's email accounts?

Thanks in advance