Microsoft Security Essentials para Windows Vista / 7 4.8.204.0 (64 bit)

Microsoft Security Essentials (MSE) is a Microsoft antivirus, which in addition to being free integrates seamlessly with the operating system.

This program includes several detection and protection systems to keep your computer completely away from threats.

This is the program that will eventually replace Windows Defender, so if you're using it you can go thinking about the change because they will not update it much longer.

It is not the best antivirus you can have but knows the structure perfectly so as a second option of protection is the best you can choose. It consumes few resources and is easy to use.