compromised machines and entire network health

[Arie Kachler]

Hello,

In the past several years, we have had a few incidents of servers of 
customers that are compromised and then flood our entire network and 
bring down almost everything. The sql slammer worm for example.

Is there a solution to this? I know all computers should be kept up to 
date so this does not happen, but most times customers are not as 
attentive to patches as we sysadmins are.
Assuming that there will always be machines with security issues, is 
there a way to prevent a compromised computer to bring down an entire 
network?

Any suggestions will be greatly appreciated.

Arie Kachler