I Really Like This ZDNet List Of Security Utilities
This is a really excellent list of security applications and sites that you can use from a PC and at least one (OpenDNS) that could be used from any machine: http://content.zdnet.com/2346-12691_22-95490-1.html
The author shows a screenshot of each tool/site and explains how it can be used to protect you.
I thought that I knew the basics because I was used to using AdAware (or SpySweeper), ZoneAlarm, and AVG to secure PCs in their basic respects. But this list taught me a whole list of new tools and also recommended some alternatives to my old favorites that I'll have to check out.