As part of their Protect Your PC initiative, Microsoft seems to have partnered with Computer Associates to give away a 12-month subscription to their EZ Armor Firewall and Antivirus Suite.
If you don’t already have up-to-date antivirus software like McAfee or Symantec/Norton running on your system, go get it.
Also, if you haven’t already set up Automatic Updates in Windows to get the latest patches as they become available, and/or you’re on a broadband connection and don’t have a firewall configured, go to Microsoft’s Protect Your PC site to automatically set up Automatic Updates and the Windows Personal Firewall.
The most important reason to configure Automatic Updates is that it will be the primary delivery method for the recently released Windows XP Service Pack 2, which, in addition to the latest patches and fixes, includes enhanced security features like a completely revamped Personal Firewall that’s enabled by default, a popup blocker, and other security features. The best way to make sure you get SP2 is to have Automatic Updates enabled (it’s already available in its final form to beta testers and MSDN Universal subscribers).
I spend most of my time in my day job dealing with security (patching, antivirus, etc.), so I know that if everyone took these steps to protect themselves, the virus writers would have a lot harder time wreaking havoc as much as they do. So be dilligent, and protect yourself!