We know that since a couple of hours (wrote this 16. Jul 2008) we have offered the newest update for MOSS and WSS V3. All the needed information for this Infrastructure Update you can find in the official team blog of the product group.
Announcing- Availability of Infrastructure Updates
With our current experience we would suggest the following order to update SharePoint.
Language packs are available: http://www.microsoft.com/downloads/results.aspx?DisplayLang=en&nr=20&freetext=sharepoint+language+pack&sortCriteria=date
All needed information to install Service Pack 1 http://blogs.msdn.com/sharepoint/archive/2007/12/11/announcing-the-release-of-wss-3-0-sp1-and-office-sharepoint-server-2007-sp1.aspx
WSS language packages for build 6317 http://support.microsoft.com/kb/953484 How to download? Please check in the left upper corner:
At the end go through the blog of the product group: http://blogs.msdn.com/sharepoint/archive/2008/07/15/announcing-availability-of-infrastructure-updates.aspx and install the needed update for WSS and MOSS.
Please understand that an update of a complex server application is not that straight forward you experienced with Office client applications. It will be a small project.
Remarks: The language specific WSS hotfix package with build 6317 (KB 953484) is available in all needed languages. The MOSS Infrastructure Update contains also language specific updates.