Why you just want admin to see the previous tab, the idea is if the users deleted something by mistake they can go to their previous version to retrieve it. If only admin can do that, they will call you all the time.
*** Improved by Wrobinson on 04/20/08 ***
That is how the feature works by design. You do not need to install client software for this to work, except for clients prior to Windows XP. By default, everyone that has access to the file share can use the previous versions feature.
This is really intended to be a benefit for end users to reduce the burden on IT staff, so if you do not intend to use it in this manner, then perhaps disabling the feature altogether is a better idea, or only enabling it for users personal folders such as home drives instead of public file shares is a better option. Of course, this means that the private and public areas would have to reside on different volumes.