Let's make the difference between MU and WU6 very clear. I've been a beta tester for both products, and while I didn't spend as much time as I wanted looking for bugs in both, I know enough about their purpose to explain. WU6 (WIndows Update v6) only scans for and offer updates to Windows, IE, Outlook Express, WMP, etc. all things that come with the OS by default. It also offers drivers for hardware, although, as you should know, using WU drivers is at great peril to the health of your machine. You are always better off with drivers direct from the manufacturer web sites instead. This is really the same Windows Update we've always had, with a new look. Nothing has really changed with Windows Update since the first versions except the ability of the Windows Update client to download updates in the background and notify you so you can install them right away instead of having to wait for everything to download. MU (Microsoft Update) currently does everything WU6 does and additionally includes support for Office (at least XP and 2003, although, maybe back to Office 2000, I don't remember). The idea is that eventually ISA, Exchange, SQL Server, IIS, etc. will also have support added to MU so you basically have a one stop shop for all of your updates for all of your machines, regardless of the Microsoft software installed. The new Microsoft Baseline Security Analyzer is part of this push to develop better tools for keeping your machines up-to-date. WSUS, WU6, MU, MBSA2, all of it is designed to provide end-users and admins with easier ways of staving off viruses and exploits more quickly so the spread of viruses is lessened and Microsoft isn't blamed for so many "bugs" and security problems. This is kind of the beginning before Microsoft launches that new service that will provide updates, anti-spyware, anti-virus, and computer maintenance in a yearly subscription-type service (I forget the name of it). As of right now most of the additional scanning tools for the other Microsoft applications is still in progress for MU and will be added at a later date. I think Microsoft figures that server admins should be smart enough to update their server apps themselves as necessary. At least, they SHOULD, but they eventually will add support for the other apps because as we know from the past experience with viruses like NIMDA and Slammer that some admins DON'T.