Every time Microsoft patches Windows, the obsolete versions of earlier files and their settings are normally stored in the WinSxS folder( C:\Windows\WinSxS) . This helps if you needed to roll back a patch, Windows can pull it out from the previous version stored in the WinSxS folder. But it consumes huge amount of disk space. You can't just manually delete everything in that folder, because some files are needed if you want to roll back a Windows Update .
Microsoft has recently released a tool "Windows Update Cleanup" for Windows 7 that adds a new option in the Disk Cleanup tool.With this update (KB 2852386) you can free up several gigabytes of hard drive space .Once you have it installed, run Disk Cleanup and click the "Clean up system files" button to find the new Windows Update Cleanup option.After you install this update, you can use the Windows Update Cleanup option to delete Windows updates that you no longer need.
Right-click on your C: drive -> Properties-> Disk Cleanup button .Here you can see a summary of what files Windows can clean up -- temporary files, Recycle bin and log files. It is not bad , if you are able to retrieve 1GB to 3GB -- or more -- of C: drive on all of your Win7 SP1 machines .
To enable you to roll back to previous updates, updates are stored in the WinSxS store even after they are superseded by later updates. Therefore, after you run the Disk Cleanup wizard, you may be unable to roll back to a superseded update. If you want to roll back to a superseded update that the Disk Cleanup wizard deletes, you can manually install the update
Download the update package for x86-based versions of Windows 7
Download the update package for x64-based versions of Windows 7