MOTM

> I have been using Mozilla Thunderbird for some time now. It's very nice
> and there's a number of security features built in - you can stop remote
> graphics from loading - JavaScripts will *not* run unless you tell them
> to - executables are prohibited from doing so - there's built-in
> configurable "spam" filters as well. You won't be disappointed.

FWIW I was disappointed with Thunderbird. I really wanted to like it, but
after the third time it screwed up while downloading my incoming email, I
had to give up on it. OTOH I am happy with the Mozilla browser.
 
In addition to AdAware and Spybot Search & Destroy (and you do have to use
both, in my experience), I've recently started using something called
Bazooka Spyware Scanner. It has found stuff on my system that neither of the
above programs have found. It's not quite as easy to use as the other two,
but it seems to be worth using.
 
> For those of you on high-speed connections - install personal firewall
> software that monitors incoming connections for you and will ask you if
> a connection is to be allowed or denied.

And go here and find out how well your firewall works:
http://www.grc.com/ 
(Use the ShieldsUp! test)

And since no-one else has said it explicitly here, keep your OS up to date.

--Adam