Scott the blaster worm or W32 as it is known can be handled by First by downloading the Patch from Microsoft, then before instalina you HAVE TO DISABLE SYSTEM RESTOR, this is done by Right CLIK on MY COMPUTER Icon (WHICH SHOULD BE FOUND ON YOUR DESKTOP)then select Properties and select System Restore and HIGHLIGHT the Box
Turn Off System Restore On All Drivesand PRESS APPLY AT THE BOTTOM.
After you done that Install the Patch.
Don't forget to Revers Back the System Restore Back To as it was before.

If you have the Blaster worm you will know cause you will get a popup windown which tells you that the computer will restart in 60sec.

I would Have suggested something more simple to you when you have trouble with XP use the SYSTEM RESTOR to an earlier Date when you know you wHeren't having any trouble and the computer come brand new.
It is simple to do and very safe.

Good Luck
Tony.