I am using CA EZtrust Antivirus with XP with only SP1 and so is my wife. For what it is worth, neither of us has any problems with any of the worms running out there. I know there has been some discussions of Symantec's "problems". For what's it's worth I have been using CA since 1997 and so far it is doing the time. It costs me $19.95 for the program and $9.95 for the once a year update.