Facing a June 30 deadline to stop selling PCs with Windows XP, the world’s largest computer makers are getting creative.

Taking advantage of the “downgrade rights” offered as part of the Windows Vista license agreement, Hewlett-Packard and Dell both plan to offer machines loaded with XP well beyond June.

Technically, the computers will be Vista Business or Vista Ultimate machines that have been factory downgraded to XP at the customer’s request. In practice, they are more like XP machines that come with an already paid-for upgrade to Vista when and if the customer chooses to do so.

HP said it plans to continue selling the “pre-downgraded” desktops, notebooks, and workstations to its business customers until July 30, 2009. Dell is already pitching the same option on its Web site and promising the models will stick around long after it stops taking standard XP orders on June 18.