Windows Service to synchronise with Exchange Server Contacts

I want to write a windows service that periodically synchronises a database with the contacts in an exchange 2007 server instance.

Is this possible with Exchange Web Services or can I do this with powershell?

If I go the EWB route, does this means that I need the client to set up the Web Service end point and make it pubilc?

The client is corporate and will resist开发者_运维技巧 this request. Is there a better way?

There's no reason why you can't do it with powershell, even within a windows service written in C#. Powershell commands can be composed and executed in-process by way of referencing the System.Management.Automation assembly and working with the Runspace (powershell v1) or PowerShell (powershell v2) Types.