By Sam Oliver

Published: 08:00 PM EST

While Apple is encouraging its install base to upgrade to the latest version of the Mac OS X operating system, a new sales pitch by its Redmond-based rival to the north recommends that customers unhappy with Vista take a step in the opposite direction 'for free.'

Speaking at an event Tuesday in the nation's capital, Microsoft chief executive Steve Ballmer said his company's licensing policy allows for customers to install the previous generation of Windows should Vista not impress.

"Customers get both," he said. "I don't know how you can do better than getting both."

Baller's comments were in response to a question about whether Microsoft will continue to market retail copies of Windows XP for mainstream PCs beyond its scheduled June 30 expiration.

The Microsoft headman explained that his firm holds no such plans because any customer who wants to purchase XP after June 30 can just as easily buy Vista and trigger its built-in downgrade option.

Earlier this week, the software maker said it would extend the shelf life of XP for installations on "nettops" -- it's term for ultra-low cost desktop systems -- for an undetermined amount of time. That followed an earlier move to continue selling the six-and-a-half year old operating system for ultra portable notebook systems for up to two more years.

InformationWeek's Paul McDougall points out that a number of PC makers, including Dell, already offer business systems that have been "pre-downgraded" from Vista to XP. Though that raises the question, he says, about the accuracy of the sales figures Microsoft has provided for Vista.

"In April, the company said it had sold more than 140 million Vista licenses since the OS became available to the public early last year," he wrote. "But Microsoft did not indicate what percentage of those Vista licenses have been downgraded to XP."



Ballmer, 52, also told those in attendance at the event Tuesday that he expects to retire from running the world's largest software company within the next "9 or 10 years," at which time the eldest of his three children will be on the way to college.