This update really combines all previous updates so installation order is simplified.
- WSS SP1 (+ for all language packs)
- MOSS SP1 (+for all language packs)
- WSS December Update: x86 - x64 (separate downloads !)
- MOSS December Update: x86 - x64 (separate downloads !)
More info about that here: Announcing December Cumulative Update for Office SharePoint Server 2007 and Windows SharePoint Services 3.0
If you're extracting the MOSS December Update for 64 bit (368073_intl_x64_zip.exe) you might run into this error:
An error occurred while unzipping. One or more files were not succesfully unzipped. The error code is 110.
A workaround is to extract the archive using WinRAR (http://www.rarlabs.com/) and it will extract the files (you still need the password from the email of course).