Microsoft is ensuring that the PC market won't be hit by a slow buying season this Christmas by announcing its plans for customers who buy new computers to upgrade to the Vista OS.

Although the upgrades in most cases won't be free, they won't be full-priced upgrades, either. Rather than implementing the same upgrade programme across the board, however, upgrade offers will partly depend on the offers that PC makers decide to give. Microsoft says that the upgrade discount coupons will vary by region, but that in the US, upgrades from Windows XP Media Center Edition 2005 to Vista Home Premium, and upgrades from XP Professional editions to Vista Business editions will carry a nominal fee.

However, upgrades from XP Home Edition to Vista Home Basic and Vista Home Premium will carry a 50% discount from the boxed product upgrade price, plus the cost of shipping and handling.

Office software will also be offered with a discount coupon so that the upgrade from the 2003 edition to the 2007 edition will be offered for the cost of shipping and handling.

Microsoft is planning to defer about $1.5 billion in revenue from the second to the third quarter to take into account the cost of the upgrade plan, which will run from 26 October until 15 March.

Pocket-lint is waiting for pricing information from Microsoft about the cost of shipping and handling.