When you’re busy using your PC, you don’t want to be bothered by needless alerts. Security Essentials runs quietly in the background, only alerting you if there’s something you need to do. And it doesn’t use a lot of system resources, so it won’t get in the way of your work or fun.
Requirements:

· For XP – CPU with clock speed of 500 MHz or higher
· For XP – Memory: 256 MB RAM or higher
· For Vista / W7 – CPU with clock speed of 1.0 GHz or higher
· For Vista / W7 – Memory: 1 GB RAM or higher
· VGA (Display): 800 x 600 or higher
· Storage: 140 MB of available hard-disk space
· An Internet connection is required for installation and to download the latest virus and spyware definitions for Microsoft Microsoft Security Essentials
· Internet Browser (IE or Firefox)

Why should I download Microsoft Security Essentials?

Comprehensive protection—Microsoft Security Essentials helps defend your computer against spyware, viruses, worms, Trojans, and other malicious software.
Easy to get, easy to use—Because Microsoft Security Essentials is available at no cost, there’s no registration process that requires billing or personal information collection. It installs after a quick download and Genuine Windows validation and then stays automatically up-to-date with the latest protection technology and signature updates.
Quiet Protection—Microsoft Security Essentials doesn’t get in your way. It runs quietly in the background and schedules a scan when your computer is most likely idle. You only see alerts when you need to take action.