When new service packs are released by Microsoft, I tend to wait a few weeks before installing them on my systems. Why? I’ve been burned before by ‘updates’ that make systems unstable, unusable, or even unbootable.
Before you install this service pack on a SBS 2003 server, read the official release notes. Then, read Susan Bradley’s unofficial release notes, which detail the proper way to apply the update. Update your NIC drivers, especially for Broadcom NICs prior to installation.
[update June 1, 2007]
[update June 14, 2007]
Susan has detailed notes available that describe the entire process for installing Windows 2003 SP2