I just noticed that a new best practice guide for Exchange has been released. This one discusses "all you need to know" about the Offline Address Books used by Outlook 2003. It's primarily of interest for administrators of enterprise and/or complex Exchange environments - such as Hosted Exchange deployments that in the official HE2003 solution uses separate servers for generation of OAB's.
It also explains how to use the new SP1 OAB network bandwidth throttling option and how SP1 better handles mismatched SMTP addresses (Causing full instead of partial download on Pre-SP1 systems). Check it out here and don't miss out the add'l resources section in the appendix.