These days, a Firewall should be mandatory; especially with HighSpeed.
It surprises clients to see just how many intrusion attempts are made on their
systems every day. Most of the intrusions are 'worm' type virus' looking
for an unsecured computer.

As for browser ? I have noticed a HUGE improvement in my internet
speed, NO popups, etc with FireFox. The odd Java scripted nasty
gets caught on it's way in by the AV.....but tons less than IE.