I have used many antivirus in my life. Such as AVG, Norton, Kaspersky, Avaira, Eset, Microsoft Security Essential etc. But most of the antivirus has many problem. Such as it makes the computer a slow one, it detect many important files as virus, patch or creak automatically deleted etc. But now I am happy to say that Microsoft security essential is the best all of them. It has many important quality to be the best antivirus. the most important characteristics is ti has no effect on computer performance and it very lite. You can use it in a very low configured computer. You are very welcome to use it. Thank you. K.H.