Article found here.
Windows XP Service Pack 2 with Advanced Security Technologies Review
Note: Windows XP Service Pack 2 hasn't shipped yet, so I'll be updating this review with new screenshots and information in the days ahead.
Last summer, Microsoft was prepping a dramatically different Windows XP Service Pack 2 (SP2) release than the one we're soon going to get. Back then, the plan was to deliver a simple set of critical security patches and hot-fixes in a convenient single install, combined with all of the updates and fixes the company had shipped a year earlier in XP Service Pack 1 (SP1). Then the Slammer worm hit and everything changed. Microsoft corporate vice president Jim Allchin, who knew the company was prepping a sweeping set of security improvements for inclusion in Longhorn, the next major release of Windows, also knew that Longhorn was years away and would arrive far too late to stop future Slammer-type attacks. Finally, Allchin decided enough was enough. He ground Longhorn development to a virtual standstill and told the Windows development team it had a new priority: Deliver a reenergized Windows XP SP2 that would include many of the security enhancements Microsoft had planned for Longhorn. And get it done as soon as possible.
Article is continued at the above link. Too much info to post here.