In message , Sacha
writes
You say a 'simple firewall' but which, how do I find and instal it? I'm a
computer user of the switch on the engine and drive variety.

Pass on Mac firewalls.

However, if you are on broadband behind router (using something called
NAT) - which consumer routers do by default) then I wouldn't worry about
it, this and the other protection built into them are good enough. I've
been running our PC's without software firewalls in such manner for a
few years now with no problems (without it I had an infection within 10
minutes once).

They do have a small benefit in also monitoring outgoing communications.
But unless you expect to be picking up lots of Trojans or viruses trying
to email themselves out etc. then really isn't worth it IMO

As for Mac viruses, yeah there a few - though AIUI no really actively
attacking OS X, but really it doesn't seem worth worrying about if you
are reasonably careful user.

If I was a Mac user I'd probably use ClamXav which is free:

http://www.clamxav.com/

Though I don't agree on the rationale they have for scanning incoming
and outgoing emails - it's not something I do here and we use Windows -
--
Chris French