During Microsoft’s Most Valuable Professionals in Seattle, CEO Steve Ballmer had one thing to say about Windows Vista, one year after its release: it’s “a work in progress.” Just one month ago, Microsoft released Service Pack 1, fixing a number of issues that have emerged during the past year through quality improvements, improvements to the administration experience and support for emerging hardware and standards.

As Ballmer said at the conference, there’s still work to be done on Vista: “A very important piece of work, and I think we did a lot of things right, and I think we have a lot of things we need to learn from,” he said. “Vista is bigger than XP. It’s going to stay bigger than XP.”

At the same time, Ballmer said Microsoft has been working on some essential steps for Windows Vista, nevertheless, the most important thing will still remain customer feedback: “Top of mind for me, for Ray [Ozzie], for the senior team here, is making sure that we continue to drive forward and take the good work that we did in Vista, take the chance for improvement and progress and drive forward.”

At the end of March, consumers started complaining of numerous flaws, while at the same time Microsoft offered free support for anyone who has trouble installing SP1, whether they were using a purchased copy of Windows or it came with their HP laptop.

There are still a lot of customers using Windows XP, and at the same time, there are a lot of customers who opted for Windows Vista. “As long as those are both important options, we will be sensitive and we will listen and we will hear that,” Ballmer said.