Yes, but not built in to xp. You'll either need thrid party software or a
hardware router/firewall. In our office I have the firewall set to block
internet access(port 80 & 8080) for specific ip address. So anyone on the
network that's has a restricted ip address gets blocked out of internet and
instant message programs. Email still works for all cause email uses
different ports. I favor the firewall solution as software can be bypassed,
disabled, changed, etc, by the users if they are good enough. The firewall,
only I control that.