Microsoft Security Essentials is more than a simple antivirus. It scans your computer for other malware as well - spyware, adware, and Trojans. Compared to the best computer security suites, Microsoft Security Essentials cosumes less resources and is easy to use. It includes Windows Defender (Microsoft's free anti spyware) as well.
Developed by Microsoft, the anti-malware software is free to download and use. With real time virus and other malware definitions download, your computer stays protected. The security package does not however, carry a firewall. I recommend you use a free firewall such as ZoneAlarm or Comodo firewall to maximize security for your computer(s). You may also use the Windows firewall if you are using Windows Vista or Windows 7.
This guide on Microsoft Security Essential brings together, the several tips, tutorials, and troubleshooting articles located on Brighthub.