Microsoft has released service pack 3 for Office 2003. This service pack integrates the tools that you previously had to download on your own for Office 2007 compatibility, so it's worth installing if only for that. Of course, there are also the updates... Microsoft's servers are currently crawling along due to demand. Direct download link here.

"For businesses, the service pack is a crucial update that addresses security issues around legacy file formats and add-ins using the Microsoft COM (component object model) and privacy concerns regarding hidden metadata."