Microsoft Security Essentials is very light weight program. This is fast running antivirus. Download it from here. It is automatically updated on initial start.
Microsoft developers have made really a wonder and easy to use antivirus.
Microsoft Security Essentials
|File Type||Exe file|
|Hash||DY821544585 - Use this if you want to report this file|
All files are scanned routinely for viruses. You can also report any file whether it may contain virus or missing by using our conact email: firstname.lastname@example.org