I do find that tools such as ccleaner and revo uninstaller are great programs, but one I am most impressed with is System Mechanic Professional. Alas, this software is NOT free, but it is one of the best tools you can find. It will do pretty much any kind of maintenance you can think of. You can also set it so that it does the maintenance automatically, so you practically never have to bother it.
[http://iolo.com/system-mechanic/pro/|Iolo System Mechanic Professional]
For businesses: http://iolo.com/smb/
For 150 users... yeah, that's kinda expensive, but instead of displaying a price, it displays a button where you can contact iolo, so maybe they have some sort of deal?