The ones I use are on my recently reinstalled laptop are:
Firewall: Zonealarm (free version)
AntiVirus: Avant AntiVir (free version)
Spyware remover: AdAware AND Spybot
Office Suite: OpenOffice 1.1 for Windows
Microsoft Baseline security analyser, it analyses your Windows, Outlook, SQL Server, Exchange Server, IIS, IE settings and lets you know what level they currently are at, what level is recommended and how to set them to the recommended level
A small utility from Gibson Research called "SocketLock". What it does is remove the Full Raw Sockets capability from Windows. You can read about it at
www.grc.com
Sean