The biggest area of fixes in this release relate to changes in the handling of administrative time, actual work and calendar exceptions – and this is embodied in fixes on both the server and client. Best to patch both to this release to get the full benefit of these fixes, but this isn’t a requirement and will not break anything if you stagger the loading of client and server patches.
In Rob’s words, first some details of getting ready to apply the CU, with either SP1, or preferably SP2, and then the CUs themselves:
This CU include a number of fixes, so Microsoft strongly recommends that you test this in a test environment based on your production environment before putting this fix live in production.
The article below provides information on how to deploy the Project Server Cumulative Update.
Deploy cumulative updates (Project Server 2007)
We strongly recommend that you install WSS and Office Servers 2007 Service Pack 2. The KB articles below provide information on how to download and install SP2 if you have not already done so.
Description of Windows SharePoint Services 3.0 SP2 and of Windows SharePoint Services 3.0 Language Pack SP2
Description of 2007 Microsoft Office servers Service Pack 2 and of 2007 Microsoft Office servers Language Pack Service Pack 2
Description of Office Project 2007 Service Pack 2 (SP2) and of Office Project Language Pack 2007 Service Pack 2 (SP2)
The server patches require that WSS and Office Servers 2007 SP1 be installed. For clarity, SP1 is required and SP2 is strongly recommended. Here are the links to the SP1 Server Patches for your convenience:
Description of the 2007 Microsoft Office servers Service Pack 1 and the 2007 Microsoft Office servers Language Pack Service Pack 1
How to deploy the 2007 Microsoft Office servers Service Pack 1 and Office Server Language Pack 2007 Service Pack 1
The Server CU is released in two different versions. The first version is in Individual Packages specific to a particular product like WSS and Project Server. These are smaller downloads but they do not include language packs or patches for other products so patches for those products would have to be downloaded and installed separately.
The second version is the Server Rollup Packages. This is a set of two rollup packages which contains all the fixes for WSS, Project Server and MOSS. These packages should be used when MOSS is part of the deployment and/or you have language packs installed. The Server Rollup Packages are much larger (~200MB each) but they will greatly simplify MOSS patch deployment.
You can read about the fixes included in the December CU from the following articles:
Note: This CU contains an important fix for a group of Actual Work issues surrounding Administrative Time and Calendars. There are fixes for this issue in both the Client and Server patches. As such, we strongly recommend that you install both the Client and Server patches from this CU. This is not a patch requirement, however, as there will be no added negative effects if only the server or client are patched. You will just not have the whole fix until both patches are installed.
Server Rollup Packages:
Description of the Windows SharePoint Services 3.0 Cumulative Update Server Hotfix Package (WSS server-package): December 15, 2009
Description of the Office SharePoint Server 2007 Cumulative Update Server Hotfix Package (MOSS server-package): December 15, 2009
Individual Product Packages:
Description of the Windows SharePoint Services 3.0 Cumulative Update Server hotfix package (Sts-x-none.msp): December 15, 2009
Description of the Office Project Server 2007 hotfix package (Pjsrvapp-x-none.msp, Pjsrvwfe-x-none.msp): December 15, 2009
Description of the Office Project 2007 hotfix package (Project-x-none.msp): December 15, 2009