I just installed slackware. I'd like to know what should be the first steps to secure my machine. Now, I am literate and make good use of the skill, (in fact I'm teaching myself this whole OS), but I'd like to know what I should do to insure I'm safe while I learn. (I'm already reading unSpawn's guide.) What are the first steps I should take?

I'm on a small home network
I'm behind a NAT router
I have 2Mb/128Kb cable connection

In Windows I used a software firewall and anti virus in addition to this. I've read that Linux is less susceptible to viruses than windows, but what about software firewall? Is my hardware (NAT) firewall enough?

http://jetblackz.cjb.net/
Has an excellent Linux tutorials including security, upgrades etc.

If you're using unSpawn's Slack guide you're off to a good start

The basic stuff, especially if you're behind that setup, is to turn off unneded services, close down unneccessary ports, and get yourself a good hosts file to, if nothing else, stop showing ads on pages and slowing your 'net connection There have been many threads about all of these topics here on LQ, so I'm sure you can find them no problem.

Edit: Welcome to LQ, by the way!

Look here...

http://www.linuxguruz.com/iptables/