Many of you surely remember the tools “vsp1clean” and “compcln” which was used after service pack 1 and service pack 2 installation to remove older Windows packages which was superseded by the service pack. These tools freed some disk space and as it removed all previous Windows components it made the service pack installation permanent, meaning it was not uninstallable after running the tools.
Anyway enough with history, when you have installed SP1 for Windows 7 or Windows Server 2008 R2 you can make it permanent by using the below command.
%windir%\system32\dism.exe /Online /Cleanup-Image /spsuperseded
You can also use Disk Cleanup to accomplish this, choose to clean your system disk and then choose “Clean up system files”, choose your system disk once again and then make sure that you select “Backup files required to uninstall service pack”.
NOTE 1: As SP1 is in beta at the time of this writing, I must warn you that running the above command will make it impossible to uninstall the SP1 beta, in practice meaning you will have to reinstall your machine once SP1 final release is made available.