1st get this proggam and run it to fix the worm
h**p://securityresponse.symantec.com/avcenter/FixBlast.exe

and afther that update your system:

Windows XP:
h**p://download.microsoft.com/download/9/8/b/98bcfad8-afbc-458f-aaee-b7a52a983f01/WindowsXP-KB823980-x86-ENU.exe

Windows 2000:
h**p://download.microsoft.com/download/0/1/f/01fdd40f-efc5-433d-8ad2-b4b9d42049d5/Windows2000-KB823980-x86-ENU.exe

Windows NT:
h**p://download.microsoft.com/download/6/5/1/651c3333-4892-431f-ae93-bf8718d29e1a/Q823980i.EXE

Windows Server 2003:
h**p://download.microsoft.com/download/8/f/2/8f21131d-9df3-4530-802a-2780629390b9/WindowsServer2003-KB823980-x86-ENU.exe

greetz,