b) No.
Personally, I couldn't be less interested in policing someones hard drive and their choice in software. If a user gets infected and then becomes a disruption to the network I would take issue with the individual.
Same goes with the web serveranalogy... if I'm running a web site that is available to the public at large, I'm not about to block connections unless they're spewing junk at me.
But that's just me... your network your choice.
