Sadly, in a Windows centric environment, such as an Exchange organization, the Macs often get left behind. The Macs can play nicely with the PCs in terms of collaboration, but we can probably never expect them to have all the same features that Outlook and Exchange are capable of achieving.
On a Mac there are really only two options for accessing your Exchange mailbox, and that is an IMAP client or an OWA (Outlook Web Access) based client. Thankfully for us, most Apple computers already have both of these; Apple Mail and Microsoft Entourage. Both of these clients can interface with Exchange both over OWA or IMAP.