Deploy cumulative updates (Project Server 2007) http://technet.microsoft.com/en-us/library/dd239177.aspx  

Note: 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 http://support.microsoft.com/kb/953338  
• Description of 2007 Microsoft Office servers Service Pack 2 and of 2007 Microsoft Office servers Language Pack Service Pack 2 http://support.microsoft.com/kb/953334  
• Description of Office Project 2007 Service Pack 2 (SP2) and of Office Project Language Pack 2007 Service Pack 2 (SP2) http://support.microsoft.com/kb/953326  
• 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 http://support.microsoft.com/kb/936984/en-us  
• How to deploy the 2007 Microsoft Office servers Service Pack 1 and Office Server Language Pack 2007 Service Pack 1 http://support.microsoft.com/kb/945013/en-us  

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 June CU from the following articles:

Server Rollup Packages:

• Description of the Windows SharePoint Services 3.0 Cumulative Update Server Hotfix Package (WSS server-package): June 29, 2010 http://support.microsoft.com/kb/983311  
• Description of the Office SharePoint Server 2007 Cumulative Update server hotfix package (MOSS server-package): June 29, 2010 http://support.microsoft.com/kb/983310/  

Individual Product Packages:

• Description of the SharePoint Server 2007 hotfix package (sts-x-none.msp): June 29, 2010 http://support.microsoft.com/kb/983307  
• Description of the Project Server 2007 hotfix package (Pjsrvapp-x-none.msp; Pjsrvwfe-x-none.msp): June 29, 2010 http://support.microsoft.com/kb/983312  
• Description of the Office Project 2007 hotfix package (project-x-none.msp): June 29, 2010 http://support.microsoft.com/kb/2028571  

Note: We strongly recommend that you install Project 2007 SP2 from the information earlier in the article.

• Description of Project 2007 Service Pack 1 and of Project Language Pack 2007 Service Pack 1 http://support.microsoft.com/kb/937154/en-us  

NOTE: Microsoft strongly recommends testing within a NON-Production environment prior to rollout.

Download the hotfix from the KB Article above (KB 2028571).

Run the extracted .exe file to apply the patch to your Project Professional/Standard SP1 (or preferably SP2) client.