More info at: http://www.symantec.com/avcenter/

If you have been having problems with your browser or cannot stay connected to your Internet provider, you need to update both your antivirus definitions and Windows.  There are a couple of issues that have been addressed in the last month or so and both can have an effect on your ability to connect/stay connected to the Internet.  You may also have a problem running Windows Update if you do not update before the 15th of the month.  You would then have to get the latest antivirus definitions and the removal tool for the particular worm you have gotten.  Both Norton and McAfee antivirus programs protect against these worms and Microsoft has a patch for Windows that also protects against the security flaw.

This only affects Windows 2000, XP and NT!  Windows 95, 98 and Me are not affected.
(MS Blaster worm only affected the above versions, but keep up-to-date no matter which version of Windows you are running!  New bugs are coming out every day!)
For more information go to http://www.symantec.com/avcenter/venc/data/w32.blaster.worm.html