While Microsoft is still pushing Vista hard, the company is quietly allowing PC makers to offer a "downgrade" option to buyers that get machines with the new operating system but want to switch to Windows XP.

The program applies only to Windows Vista Business and Ultimate versions, and it is up to PC makers to decide how, if at all, they want to make XP available. Fujitsu has been among the most aggressive, starting last month to include an XP disc in the box with its laptops and tablets.