Windows Vista SP2 Service Pack Clean-up tool
Its a big update yes, raw file says its 577.4 Mb on five languages. If you want to reclaim some disk space after applying the SP2 you can run this update cleanup tool that is included on the SP2 install - compcln.exe
Windows Component Clean Tool (Compcln.exe) can be used to remove the files that are archived after Windows Vista SP2 or Windows Server 2008 SP2 is applied. It also removes the files that were archived after Windows Vista SP1 was applied, if they are found on the system. Running this tool is optional.
NOTE AGAIN: You cannot uninstall Windows Vista SP2 or Windows Server 2008 SP2 after you run this tool on an image.
Here is a complete post with screenshots of Windows Vista SP2 Service Pack Clean-up tool
More info are available on the Windows Vista Service Pack 2 Deployment Guide at TechNet: http://technet.microsoft.com/en-us/library/dd335037(WS.10).aspx