Accessing contact list in exchange

Hello group,
we are running a SBS2003 and I'm trying to access the contact list from the
exchange server from a ASP.NET webapplication.
The IIS is running on the exchange server and I develop the solution from a
remote machine. What software/libraries do I have to install to use cdoex,
for example?
Is cdoex the best option for accessing the contact-list?

Thanks for any hints and tips,
Andreas