When Microsoft acquired Giant's Antispyware product and released the first beta of what became Microsoft AntiSpyware, I was pretty impressed. It was a good, solid product with a number of useful features that no other free anti-malware application had. Realtime monitoring in a free product was a huge plus, and a community-driven effort through SpyNet was a great idea.

Then Microsoft decided to call the product Windows Defender and announced that it would be a part of Windows Vista. Now Beta 2 of Defender has been released for XP, and it almost looks like a brand new product. Fortunately, most of the changes are for the better. The UI has been greatly simplified, and the whole app has been redesigned to be as unobstrusive as possible. In fact, once installed, you won't even know it's running, because the icon in the system notification area disappears and comes up only when the user's action is required. The number of popup notifications has been significantly reduced as well, so when you see an alert now, you'll know it's important.

I was also really glad to see a native 64-bit version. It seems like Microsoft is finally taking XP x64 seriously. First the IntelliPoint and IntelliType software, and now this. All that's left for me is an x64 version of Windows Desktop Search. I hope that's in the pipeline too.

Paul's got a review of Beta 2 with lots of screenshots on WinSuperSite as well.