My father helps run the computer network for a small public library in 
Maine.  They run a W2000 server (donated by MS) that provides about 15 
machines with Internet access, book checkout data, card catalog info, 
etc.  They also host the library's website from this machine.  As you can 
guess, they have been Nimda'd & everything else imaginable to death.  They 
have a T1 line to a Cisco 1605R router (no firewall software installed) to 
a network hub.  I first suggested they insert a Linux box running IPcop 
before I knew they had the router.  What do you think the best, easiest, 
cheapest setup would be?  Linux firewall box, purchase software for the 
Cisco, purchase a simple Linksys router w/firewall software already in 
it....    Keep in mind that these are all library volunteers with VERY 
little knowledge in this area.  It's hard to walk them through stuff from here.