Microsoft finally released Windows Defender final version and take out from beta version. Basically Windows Defender is an free program that helps protect your computer against pop-ups, slow performance, and security threats caused by spy ware and other unwanted software. meanwhile, windows defender also provides protection on your unwanted changes to Internet settings, and unauthorized use of your private information especially on your web browser.

These are the improvements that Windows Defender has received since the previous release Windows Defender beta 2:

• Enhanced performance through a new scanning engine.
• Streamlined, simplified user interface and alerts.
• Improved control over programs on your computer using enhanced Software Explorer.
• Multiple language support with globalization and localization features.
• Protection technologies for all users, whether or not they have administrator rights on the computer.
• Support for assistive technology for individuals who have physical or cognitive difficulties, impairments, and disabilities.
• Support for Microsoft Windows XP Professional x64 Edition.
• Automatic cleaning according to your settings during regularly scheduled scans.

if you still using the windows defender beta 2, i highly recommended you upgrade your current windows defender because the support of windows defender beta 2 will be until December 31 this year and expired.
Windows Defender Download Page
Direct Download Link for Windows Defender 32-bit
Direct Download Link for Windows Defender 64-bit

Updated: You can check out this post – How to bypass the WGA validation when you install windows Defender.