Microsoft is sensitive to some projections by industry analysts that Vista's sales will be initially sluggish, with consumers and corporations eschewing features such as Vista's graphical and security enhancements.

The company has taken a number of steps to raise buzz and sales of the operating system.

For instance, having missed the traditionally key holiday shopping season, Microsoft is offering vouchers to consumers who bought their PCs in the past three months that can be redeemed for Vista upgrades after its official release on Jan. 29.

It also gave away free laptops installed with Windows Vista Ultimate to influential technology bloggers.

Microsoft announced another upgrade program for customers Wednesday. Called Windows Anytime Upgrade, customers will be allowed to upgrade to more powerful versions of Vista by simply clicking within Windows, purchasing an upgrade from Microsoft's Web site and downloading an activation key.