Proxy questions, etc

[Darryl Hoar]

Greetings,
I have a couple freebsd servers on my network.  I'm trying to solve the
following
problem:   Some users (don't know which) are accessing pornographic stuff.
In addition, porno pop-ups are appearing on machines.

Is it pratical to use a proxy server (squid ?) to try and prevent access to
pornographic websites ?   From my reading on proxy's, it doesn't seem
practical.

How are others handling this issue ?

thanks,
Darryl