Microsoft Downloads to Keep Your Computer Safe
To begin with, we'll talk about the freebies from software giant, Microsoft, whose operating system is used on more than 70 percent of computers worldwide.
Microsoft Security Essentials
Microsoft Security Essentials (MSE) is replaces OneCare as MS's protection solution. OneCare included a firewall, while MSE. However, OneCare was subscription based software and MSE is free for use on genuine Windows installations. It also includes the Windows Defender anti-spyware discussed below.
MSE takes few minutes to install and is easy to use. The only knock is the aforementioned lack of firewall, which is true of many free security products. It's also a moot point since MSE is meant to run alongside Windows Firewall, which comes with the OS. Still, you can turn off the Windows firewall and use MSE with some other firewall. If you ask me, I would recommend one from ZoneAlarm or Comodo. Both are free to use while offering robust protection.
Microsoft Windows Defender
MS also has free anti-spyware. It comes preloaded on Windows Vista and Windows 7 but if you are using XP you'll have to download Defender from the Microsoft website. If you are using Microsoft Security Essentials, you need not download Windows Defender as the latter is included. Like Essentials it is easy to use (you can largely install and forget it). It offers you real time protection against malware. You can also set a schedule for the software to scan your system on a regular basis.
Microsoft Malicious Software Removal Tool
Known as MSRT for short, you can get this product from Microsoft if your Windows installation is genuine. To download the MSRT, visit the Windows Update website. While the Express Install option will automatically install it, and several other updates, to your computer, you can also select Custom Install if you wish to install only MSRT or the updates for it product.
MSRT is updated monthly and updates are available on the second Tuesday of each month. Make sure you have the latest updates (manually by visiting the Update site or set the Windows Updates to Automatic in Control Panel).
MSRT runs in the background to scan your computer in an unobtrusive way and will only alert you if it finds someting. To start it manually (say you think something is wrong), type MRT in the run dialog (Windows Key + R).