Web Access Control.

Hi.

I am trying to help a friend who has a small business.
He has a small network, 5 Windows 2000/XP workstations, and around 12
thin clients, all networked ins Windows 2000 domain/Active Directory, as
he purchased it and is stuck with it now.

He wants to control web access and web surfing and monitor.

And since he is almost without money, I suggested that we install Red
Hat Linux and some firewall proxy software and use that as the gateway
for his web access.

My question here is, what do you recommend that will achieve the
following:

1. Authenticate users when opening internet explorer.
2. Doesn't require proxy client installed.
3. Logs all sites visited.
4. Provides a web based access to read the logs, and to block offensive
URLs.
5. Has basic control over the cache.


Please remember, I am still a learner, while I could install few
software and configure them, I have never looked at anything like this.
If this was asked and answered before I apologize in advance.


Your opinion is always welcome.

Thank you.