Great Stuff..

IPTABLES (which is what Firestarter is controlling) is pretty much the one stop shop you need, it doesn't look it but the thing is used in a lot of commercial firewalls (Watchguard being the most noteable off the top of my head).
Really how you go about patching depends on your distro. Suse (last time I used it) has YaST which can autoupdate from them, RedHat/Fedora has yum and an assortment of other utilities and Gentoo is a cow (but I love it so).

However, and people will yell at me for being blazaie about it, 90% of security alerts I've seen are local privledge escalations from a local terminal only; basically someone needs to be sat physically at the computer to make use of the flaw, so I don't tend to update that often.
Making sure your root account has a nice beefy password and can't login from a SSH shell will however kill off most threats.

Is Linux safer by default? Yes and no. If you're running a server with lots of oddbod scripting sites on it (say phpBB2, Wordpress 1.5.x, etc.) that aren't kept up to date then yeah bad juju can happen. But if your running it as a desktop with a decent iptables config telling everyone to bugger off who knocks on the door... your as safe as houses IMHO.

Edit.
If your running headless and facing the internet. It's a good idea to just tell SSH to only authenticate via key based systems, rather than risk someone managing to brute force a user account. PuTTY & Pagent are your friends in doing this.

yep. Headless machines are just that, no monitor/keyboard/mouse attached to them (or attached via KVM devices).

A few freeware apps for you Mac users

Perian - Quicktime plug-in to play AVI, FLV, 3ivX, DivX, etc etc
http://perian.org/

ImageWell - quick capture and upload utility
www.xtralean.com/IWOverview.html

Adium - Instant Message App - AIM, Jabber, MSN, Yahoo etc
www.adiumx.com/

Azureus - excellent Java bittorrent client (use the beta for Intel Mac's)
http://azureus.sourceforge.net/

ffMpegX - video format converter - converts almost everything
www.ffmpegx.com/

TiVOTool - backup TiVo recording or stream over your network
www.tivotool.com/

OSXPlanet - very cool live earth images on your desktop
www.gabrielotte.com/osxplanet/main.html

SafariBlock - ad-blocking for Apple's Safari
http://fsbsoftware.com/

PureFTPd - powerful FTP server
www.pureftpd.org/project/pure-ftpd

CocoaMySQL - nice GUI MySQL editor
http://cocoamysql.sourceforge.net/

MacTheRipper - Backup your DVD's
www.mactheripper.org/

site said:

PC WIZARD 2006 is also an utility designed to analyze and benchmark your computer system. It can analyze and benchmark many kinds of hardware, such as CPU performance, Cache performance, RAM performance, Hard Disk performance, CD/DVD-ROM performance, Removable/FLASH Media performance, Video performance, MP3 compression performance.

PC Wizard 2006.

This should sort you out:

http://spambayes.sourceforge.net/

Only problem is that there isn't a free version of 7.5 (or am I being thick?)

for spyware removal use Hitman Pro www.hitmanpro.nl/hitmanpro/ (program is all in one, also english)

If anyone is using Windows Defender beta version, it is now time to upgrade.
Microsoft has released the finalised version, and will discontinue updates of the beta version as of 31st December.
Windows defender can be downloaded--> www.microsoft.com/security

Only one I can think of is Foxit, although I haven't tried it - got mixed reviews from what I've read.