If you still run Microsoft Vista (what are you crazy? update to Windows 7, it'll be like getting a new computer) and you haven't got SP2 (Service Pack # 2) installed yet, get on it.
MS is not going to offer any more patches to SP1.
If you don't have SP2 installed download it now. You can use automatic update, or you can download it from here and burn it to a CD if you have more than 1 computer that needs it: