You've actually asked a question that is more religious than technical... the key words being "Max Security".
To setup internet access for 30 people is easy (assuming they're all on the same LAN). Max Security is a differnet animal with many different definitions.
Generally speaking, you'll need a T1/DSL/Cable connection, a router, a firewall, and a switch.
Use access-lists on the router to block the basics (10.x.x.x, 172.16.x.x, local addresses, etc...)
Use NAT on the router or firewall if your ISP doesn't give you enough IP addresses.
Configure the firewall for "max security" ;)
The switch will allow everyone to talk to the firwall which talks to the router which talks to the ISP.
Mick.
