Restricting internet browsing to specifi

There are many Proxy Servers' available which can be used to define different browsing criterias', one of which is time-based. It will help answering your querry if u provide more info on your setup, ur needs etc.
To give you an example, In an ISAServer, you can define "Policy Elements", "Access Policy", "Cleint Address Sets" and using all of them, u can define a "Rule" which will say that this User group, can browse only these things, and only between bla-bla time.
Maybe u shd provide moredetails.

humm an it guy seemed to answer your initial question quite thoughly yet you rejected his answer and asked another question.

First Windows ISA server knowledge base has articles on how to setup policy rules in ISA server [see: http://support.microsoft.com/default.aspx?scid=kb;en-us;300492 ] This article has a step by step approach under "How to make a rule Exceptions" to restrict users access to certain days & times.

I think you should rethink your rejection of An IT Guy's answer, award him the points and then ask another question which addresses configuration of ISA server to restrict days and times.