Windows Vista customers can now receive the first service pack for the operating system via the Microsoft Automatic Update service, Microsoft said Wednesday.

Windows Vista Service Pack 1 will download automatically to PCs that have the automatic update feature of the OS turned on, the company said. Previously, Vista was available to customers via Windows Update, but people had to specifically download it.

Not all customers will receive SP1 immediately via Automatic Update, however. The company is distributing it in phases to "ensure a seamless download experience," Microsoft said. A timeline for when all customers would receive Vista SP1 via Automatic Update was not immediately available.

SP1 is a rollout of software updates that fix bugs and glitches in Vista and is seen as a milestone that will inspire many customers -- especially those in the business market -- to adopt the OS. In fact, in a recent report, "Building the Business Case for Windows Vista," Forrester Research said more business customers plan to upgrade to Vista now that SP1 is available. This comes as no surprise, considering companies often wait for the first service pack after a major Windows release to update corporate desktops.

However, even SP1 will not guarantee that enterprises and business customers currently running XP or an earlier version of Windows will upgrade, as some have said they would skip the OS altogether. The same Forrester report said as much, although the research firm is recommending that companies don't skip Vista because they would not be well-positioned for future versions of Windows if they do.

Microsoft has acknowledged problems with application compatibility and lack of driver support, among others, that customers have had with Vista. It says SP1 and other updates that the company continues to make should remedy these problems. What the company hasn't said is why there were so many problems with the OS when the company had more than five years between the releases of Windows XP and Vista to ensure a smooth transition.

In fact, Microsoft seems to be looking past Vista to the future rather than addressing continued concerns about the product. In a meeting with reporters on Microsoft's Redmond, Washington, campus on Tuesday, a presentation on Windows Vista turned out to be anything but that.

Instead, Shannen Boettcher, general manager of Windows product management at Microsoft, discussed future plans for tools to virtualize corporate desktops and applications. He implied this would be an important aspect of the Windows client OS going forward, but was vague about timing.

Apart from that, Boettcher's main discussion specifically about Vista was a mention of its green-computing merits. He asserted that upgrading 10 corporate desktops to Vista is comparable to taking one automobile off the road in terms of reducing carbon footprint.

When asked about criticism of Vista in the marketplace and why there were so many problems after five years of development, Boettcher had little to say other than to acknowledge that Microsoft did not do "a very good job in preparing people for when we shipped" Vista.

He added, however, that the upgrade cycle for an OS doesn't begin to pick up until 12 months to 18 months after the OS is released, and since Vista was released to business customers in November 2007, it's right on schedule.