NOD32...it already has best in class antivirus, antitrojan, antirootkit, and antispyware.
Along with windows defender built into any OS from XP on. That is all you need.
Only invest in a software firewall if you are connecting bareback to a cable/dsl modem and not through any type of router, which all serve as a hardware firewall via NAT.
But honestly, just buy a hardware router/firewall. Period. You don't need anything more than a hardware firewall and BULLETPROOF, worth paying for, Antivirus like NOD32 or anything with the KAV engine.
And if you want to go cheap, go with a free AV solution. And when that freeware AV software fails (they always do), do what the professionals do, download the trial version of NOD32 (or KAV), clean up your machine, and then pay for the software.

All the rest of the antispyware applications were made irrelevant when the giant branded software was purchased by MS and integrated into XP and Vista as Windows Defender, and when NOD32 added antispy/malware into their detection engine.
Anything by Norton/Symantec (except for Ghost) is the worst thing you can ever do to your computer, followed closely by Zonealarm. Ahem.