Update your PC. I still see PCs with Windows XP Service Pack 1. This is not a secure operating system and should by updated immediately. But how do I know if I still only have Service Pack 1? Good question. The easiest way to tell is to watch your PC start up. There are small coloured lights which go from left to right as it loads. If the lights are green, you have SP1, if they are blue, you have SP2 or SP3. This only applies to XP machines. Vista currently has green lights, with or without SP1.