* Download the vCenter Server 4.0 update package with all the modules from: http://downloads.vmware.com/d/details/vc40u1/ZHcqYmQlcCpiZGVqZA==
Note: You will need a valid vmware login to download the package.
* The package name was VMware-VIMSetup-all-162902.zip
* Unzip the package
* BACKUP YOUR EXISTING VirtualCenter 2.x database first!!!
* Double click the autorun.exe in the extracted folder.
* Followed the upgrade instructions. We didn’t run into any trouble with the upgrade.