As you might have seen the final version of SP1 for Windows Server 2003 has been released and can be downloaded from here. Others have reviewed the enhancements and new functionality in SP1 so I won't dig into that - but I wanted to inform you about a known issue with the Security Configuration Wizard and Exchange.
There is an issue with the Security Configuration Wizard when Exchange isn't installed in the default %ProgramFiles%\Exchsrvr directory which potentially could block the TCP Ports used by Exchange. The solution to the problem is simple - you should manually specify the path to the Exchange executables when SCW displays [Not found!] next to one or more of the processes in the Network Security Section.
According to my contact at Microsoft there will be posted detailed info about this issue on http://blogs.technet.com/exchange/ in the near-term future (Update - here's a link to the blog posting on You Had Me At EHLO)