Updated: Windows Vista SP1 downloadable now, ships tomorrow

Currently, items for sale are marked with the curious message, "In stock on March 20, 2008."

1:12 pm EDT March 18, 2008 - Just a few hours after Amazon told its customers that Windows Vista SP1 packages would be shipping tomorrow, Microsoft made Service Pack 1 for Vista generally available.

In a blog post just minutes ago, Windows Vista product manager Nick White acknowledged having encountered driver compatibility problems with the initial deployment of SP1, though at this point those problems aren't exactly news.

"We spent the last couple of months looking closely at reports of driver problems on pre-release builds and, to be safe, we held the public availability until March," White wrote. "We've completed our analysis and are happy to report that many of these issues were fixed between the release candidate (RC) and the final version. We identified a small number of device drivers that may be problematic after an update from Windows Vista to Windows Vista SP1."

12:36 pm EDT March 18, 2008 - If all goes as planned, the final stage of one of the most careful, highly monitored, and nervously anticipated rollout processes in Microsoft's history may at last be under way.

Web retailer Amazon is advising customers who are placing pre-orders for commercial, box versions of Windows Vista with Service Pack 1 included, that the product will be available for shipping tomorrow, March 19.

The full edition of Windows Vista Ultimate with SP1 included is selling for $299.99, with the upgrade only edition selling at $194.99. Windows Home Premium with SP1 is selling for $215.99 for the full edition, $94.99 for the upgrade edition, which is geared towards owners of Windows XP and earlier Windows clients. Amazon's price represents a discount from Microsoft's suggested retail prices, which do not appear to be changing amid the addition of SP1 to these packages.

Microsoft dropped its Windows Vista prices last month, after more than one year on the commercial market.

The "release" of Vista SP1 has been a gradual, careful one on account of the fact that some of its additions were expected to cause problems with some existing Vista customers. After its release to manufacturing in early February, SP1 was made available over the Windows Update service, to customers who were ready to test their systems and who didn't want to wake up one morning to discover Vista had changed something big.

Later, the plan was to make SP1 available via Automatic Updates, but that process was suspended for a short time after some customers complained about their computers becoming stuck in an endless reboot cycle.

The commercial release has always been planned as the last stage, though its precise date has been left floating to allow for potential problems -- and there were some -- to be ironed out during the upgrade process for existing customers.