Microsoft will be offering consumers and small businesses who purchase new PCs after October 26 free or discounted upgrades to Windows Vista and the forthcoming Microsoft Office 2007.

Both software applications are slated for general availability next January.

"These programs ensure people will have a great experience with their Windows XP-based PCs today, and an even better one when Windows Vista and the 2007 Microsoft Office release become available," said Mike Sievert, corporate vice president of Windows Client Marketing.

PCs that qualify for the Windows Vista Express Upgrade programme are identified by the Windows Vista Capable logo. Users may be charged an upgrade fee depending on the version of the operating system that comes bundled with their new system.

Consumers in the US are charged a nominal fee to upgrade from Windows XP Media Centre Edition 2005 to Windows Vista Home Premium and from Windows XP Professional, Windows XP Tablet PC Edition or Windows XP Professional x64 to Windows Vista Business or Windows Vista Business 64.

Users buying a new system that comes bundled with Windows XP Home edition are charged $50 and $79.50 for upgrades to Windows Vista Home Basic or Windows Vista Home Premium respectively, a 50 per cent discount off the regular upgrade prices.

System manufacturers will have to sign up for the upgrade programme. Dell, Gateway, HP and Sony are among the manufacturers that have committed to the programme.

The coupon programme is intended to prevent a slowdown in PC sales in the months immediately before the Vista launch. Consumers typically delay new computer purchases in anticipation of major operating system revisions.

Rumours about the pending upgrade programme first surfaced last August.

The upgrade offer is set to expire on 15 March 2007.