With Vista just out the door, Microsoft is now drawing up plans to deliver its follow-up client operating system by the end of 2009, according to the executive in charge of building the product's core components.

Last year, Microsoft code named Vista's successor as Vienna, but Fathi said he could not disclose the current name or what would be the major improvements in the release. "We've been told not to use it publicly. We're going to look at a fundamental piece of enabling technology. Maybe its hypervisors, I don't know what it is. Maybe it's a new user interface paradigm for consumers. It's too early for me to talk about it. But over the next few months I think you're going to start hearing more and more."

Vista shipped about two-and-a-half years after XP SP 2, and Vista's follow-up is expected to take about the same amount of time, according to Fathi. "You can think roughly two, two-and-a-half years is a reasonable time frame that our partners can depend on and can work with," he said. "That's a good timeframe for refresh."

Hah, nice way to stop people upgrading to Vista. If they are going to have a new one soon and I was purchasing a computer right now, I'd opt for the stability of XP and hold out upgrading until the next OS version.