MS Exchange supports a variety of methods for accessing email.
OUTLOOK WEB ACCESS
Outlook Web Access: Outlook Web Access does not require any configuration; you simply log in anywhere, and you're ready to go. Some companies are choosing to use Outlook Web Access exclusively, to simplify support so that they don't need to maintain/update Outlook software on every computer.
EMAIL SOFTWARE
Outlook (Windows): If you are going to use email software on Windows, we recommend Outlook. A free copy is included with every mailbox.
Entourage 2004 (Mac)
Entourage 2008 (Mac)
Mac Mail (Mac)
Secure IMAP (Generic)