Waldo,
Layered defense is actually user choice by need.
I can suggest a "practical" layered defense but it can vary widely by how much and by what the user does with their computer:
Proxy filter (Proxomitron is a nice one)
Firewall (Rule and Application based (Sygate/Kerio.....give versatility; Application based is much easier to learn.....Zone Alarm is the only one I recommend in this category)
Antivirus (You know the answer to this one! AVAST)
Anti-ad/spyware (SpywareBlaster and Spyware Guard work flawlessly together; Adaware and Spybot SD are nice manual scanners to include in the "anti" package)
Script Blocker (Script Sentry or Script Defender)
Cookie filter (Cookie Wall is my choice)
Popup killer (for IE engines.....use Window Shades; for AOL, Opera, Netscape......use NoAds)
Optionals:
Anti-trojan (resident is nice, but a manual necessary......Trojan Hunter and Trojan Guard seem to work well)
Process guard (many available)
Non-MS browser (I recommend Mozilla, MyIe2 or Avant)
Non-MS OE-mail client (Pegasus is excellent but unfortuantely no longer supported; Eudora is another fine client)
Tracks erasers
Encryptors
etc etc etc........
General rule: Select programs that require minimum of monitoring and run resident! You'll use a bit more memory, but will end up with less headaches.
There are thousands upon thousands of programs available in each of the above categories.....some freeware, some shareware, others payware. I have given you suggestions of the freeware that I personally use with excellent results, but you can choose similar software of other titles.
The main thing is TOO HAVE THEM!
No matter how much you install, and no matter how hard vendors try to protect your computer, there are those out there in computer land who spend their endless time trying to defeat those things that you have done and hack into your system.
Just like protecting your car.......
if you can make it difficult enough for them to get in and slow them down, they often just go someplace else!
Good luck,
techie101