There are always requests here at Microsoft for reducing the footprint that the component store takes up (\Windows\winsxs). Applying a service pack to Windows Vista or Windows 2008 will increase the size of the store even more to allow for the staging
Read More...
Read the complete post at http://blogs.technet.com/joscon/archive/2009/07/01/reclaiming-disk-space-after-applying-a-service-pack-on-vista-or-2008.aspx