In an effort to simplify the distribution of Windows Vista and make it easier for customers to upgrade, Microsoft will include the various retail versions of the OS on one DVD instead of having separate DVDs for each Vista edition, the company said today.

In the past, Microsoft distributed each version of the Windows client OS on its own disk, says our colleague, Liz Montalbano of IDG News Service. However, in a move it is calling "Windows Anytime Upgrade"--which cuts costs for Microsoft as well as making it easier for customers to upgrade--the version of Windows Vista that a customer buys will be activated by his or her product key and will be on a disk with the other editions of the OS.

For example, if a customer buys Windows Vista Home Premium from a retail store, he or she will get a DVD that also includes Windows Vista Ultimate, but the product key for the purchase will only activate Home Premium and its features and functionality, Mike Burk, a Microsoft spokesman, told IDG News Service.

"With Windows Anytime Upgrade, the idea is to provide customers with the most convenient user experience possible by enabling them to more easily and directly upgrade to a higher edition of Windows Vista from within their current edition," he said.

Consumers will have their choice of several versions of Windows Vista when it becomes available, which is scheduled for January 2007: Windows Vista Ultimate, which will cost $399; Windows Vista Business, which will cost $299; Windows Vista Home Premium, which will cost $239; and Windows Vista Home Basic, which will cost $199.

Microsoft has said it plans to urge customers to purchase premium versions of Vista in favor of Windows Vista Home Basic, the entry-level version for U.S. consumers.

Ken Fisher over at Ars Technica has a detailed blog entry on Microsoft's decision that's worth a read.