On Friday Microsoft released a the latest version of their anti-malware product, which is now called Windows® Defender (Beta 2). This software replaces the product formally known as Microsoft Antispyware. There's both 32- and 64-bit versions available to download.

I've installed it and it runs just fine, but I get an error when it tries to update itself with the latest detection signatures. I'll try a reboot and see what happens a little later on. Hopefully that will help.

The new UI is nicely done, and I like the fact that you don't have to be an administrator to run Defender.

Defender information  on Microsoft.com: Windows Defender home Product information •  Beta overview •  FAQ •  System requirements •  Release notes Support and training •  Getting started •  Beyond basics Resources for software vendors Microsoft's focus on spyware

From the Windows Defender download site:

Windows Defender (Beta 2) is a free program that helps you stay productive by protecting your computer against pop-ups, slow performance and security threats caused by spyware and other potentially unwanted software.

This release includes enhanced features that reflect ongoing input from customers, as well as Microsoft’s growing understanding of the spyware landscape.

Specific features of Windows Defender Beta 2 include:

• A redesigned and simplified user interface – Incorporating feedback from our customers, the Windows Defender UI has been redesigned to make common tasks easier to accomplish with a warning system that adapts alert levels according to the severity of a threat so that it is less intrusive overall, but still ensures the user does not miss the most urgent alerts.
  
• Improved detection and removal – Based on a new engine, Windows Defender is able to detect and remove more threats posed by spyware and other potentially unwanted software. Real Time Protection has also been enhanced to better monitor key points in the operating system for changes.
  
• Protection for all users – Windows Defender can be run by all users on a computer with or without administrative privileges. This ensures that all users on a computer are protected by Windows Defender.
  
• Support for 64-bit platforms, accessibility and localization - Windows Defender Beta 2 also adds support for accessibility and 64-bit platforms. Microsoft also plans to release German and Japanese localized versions of Windows Defender Beta 2 soon after the availability of the English versions. Use WindowsDefenderX64.msi for 64-bit platforms.