Internet Vulnerability Profiling courtesy of Gibson Research Corporation.

Are you really secure? How do you know?
Get your PC prodded and poked here and all at NO COST!

This is the first and last thing that every computer owner must do. Why? Firstly, it's an absolute eye-opener and getting your computer assessed will expose all it's vulnerabilities. You are then in a position to address those vulnerabilities and take corrective action. Once you've done that, re-test again to see if what you've done has actually worked! This also tests the effectiveness of any security products that you may have downloaded or purchased.

Shields Up!
https://www.grc.com/x/ne.dll?bh0bkyd2

While you're there, take all the other tests as well. It's mind blowing.
http://www.grc.com/default.htm

Microsoft's security analysis

http://www.microsoft.com/technet/archive/community/columns/security/5min/default.mspx?mfr=true

http://www.microsoft.com/technet/security/tools/mbsahome.mspx

Other testing services

Symantec's security advisor
http://security.symantec.com/sscv6/default.asp?langid=ie&venid=sym

Find website content that's been copied without your permission
http://www.copyscape.com/

Email security testing
http://www.gfi.com/emailsecuritytest/

Probe your firewall here
http://www.hackerwatch.org/probe/

Firewall Test, Port Scan, Spy Ware and Security Audit Choices
http://www.auditmypc.com/

Assorted website and email security tests
http://www.windowsecurity.com/securitytests/