Outlook 2007, connection to Microsoft Exchange not working

I have been trying to add an exchange server to my outlook and its keeps failing and prompting for password, it does not let me add the exchange server to my Outlook. I changed the security policy on NEtwork Security: LAN Manager Security level - Send LM & NTLM, use NTLMv2 session security if negotiated..

I am on a computer that is not joined to the domain, but in the past I have used Outlook 2007 on XP professional and it has worked fine. I have also disabled User Account Control.

I am trying to connect Outlook 2007 on Vista Business to a Microsot Exchange server. When I try to add the account, it keeps prompting me for the password, i have specified the domain on the account when i try to log in to do a check name and it does not work.

Any help would be greatly appreciated.