The latest version of Microsoft's Windows XP Service Pack 3 has been made available to all Microsoft Developer Network and TechNet subscribers. The expected ship date for the XP SP3 is still 2H 2008. For Vista owners, a public test build of Vista SP1 is expected to hit next week.

The update is mixed benefit for Microsoft. What the company should want is more Windows Vista migrations. Windows XP SP3 is expected to release about the same time as Windows Vista Service Pack 1. But the installed base is overwhelmingly Windows XP. It's not like an XP update is going to encourage IT organizations to migrate to Vista. Why switch when XP runs just fine and presumably better with SP3? One wonders what the fly on the wall heard during the Microsoft service pack debate. Surely there was one. It's easy to imagine some Microsoft product managers arguing for a long SP3 delay in favor of pushing Vista adoption, while others insisting on doing the right thing by XP customers. For a while there, given Microsoft's surprising reticence about either service pack, XP users were looking to be people left behind by the Vista bus. Vista likely will still get the preferential treatment, but XP users won't wait for a bus that may never come.

XP SP3 RC1's milestone foreshadows Vista SP1 development. Microsoft isn't about to open the SP3 testing floodgates while sending SP1 to trickle, trickle down a faucet. XP SP3's broader beta demands similar treatment for Vista SP1. I've heard from some Microsoft elves that, barring any North Pole catastrophes, Vista SP1 RC1 will be more broadly available long before Christmas. Ho, ho, ho. Have I mixed enough metaphors yet? Microsoft's development of Vista SP1, XP SP3 and Windows Server 2008 is taking place nearly in lockstep. It's raining release candidates! Windows Server is the core code base, and, at least since 2004, desktop and server OS development are closely timed, with Windows Server's timetable setting the agenda for Windows client.