If you are happy with your installation of Windows Vista SP2 (UPDATE: go here if you are not), you can remove the files, stored on your computer, that will allow a roll back. I only recommend this if you are looking to save space. With hard drives as big as they are today, I see no need to remove these files unless you are below 10% free disk space on your operating system’s partition.
Removing Installation Rollback Files
To remove the files needed to rollback to SP1:
Press Winkey+R (Start, type run, press Enter), type compcln.exe, and press Enter.
When prompted, press Y and then Enter.
The SP2 rollback files will now be deleted. If you didn’t remove the files after the installation of SP1, you’ll save even more space.
How Much Space Can You Save?
I performed a cleanup after install Service Pack 1; if you did not remove SP1’s files, you will save more space than me. However, I still saved approximately 300MB — depicted below.
Free Space Before
Free Space After
So, if you need the space, go ahead and run the compcln tool and remove those unneeded files.