Currently the WUS beta supports all editions of Windows 2000 Server, Windows 2000 Professional with Service Pack 3 and later, Windows Server 2003, and Windows XP Professional. Supported applications include Office 2003 and Office XP with Service Pack 2 and above, Exchange 2003, SQL Server 2000, and SQL Server Desktop Engine (MSDE) 2000. WUS will install security updates, non-security updates and rollup packages, service packs, feature packs, and critical driver updates.
You'll find more details about WUS in Microsoft's WUS datasheet as well as rollout help in the Deployment Guide. You can also learn more about WUS more in our article, " What You Need to Know About Windows Update Services ."