Zone Alarm 5 still is a bit buggy although it has been running fine on a W98 machine. It did not fair well on an XP. I use an older version of ZA and also have Sygate.
Avast is a wonderful AV that as far as I am concerned .... is better than the headache of Norton.
I usually run antispyware programs such as SpywareBlaster and SpywareGuard which are resident running.
Adaware is a good manual scanner for spyware, as is Spybot SandD.
Process Guard is a nice addition, and also consider a cookie filter of some kind.
Remember, that if you use Avast Home, then you need to install a script controller since only the Pro version has one.
I use either Script Defender or Script Sentry.
Browsers are another area for vulnerability.
Independent replacements for IE:
Mozilla and Firefox are top contenters with Opera running a third (only because it displays banners ads unless you "register" it....at a cost of about 39.00US. Not worth it. Green Browser has been used by forum users with great satisfaction.
Some nice IE overlays are Avant and Enigma.
You can add on so many things depending on your wishes from proxy filters to mail filters and beyond.