Lenovo said Friday it is offering free Windows 7 upgrades to customers who buy a Windows Vista PC, following a similar deal from Hewlett-Packard.

The company said that all systems sold between 26 June and 31 January with the Home Premium, Business and Ultimate versions of Windows Vista would be eligible for the update.

Lenovo said that the offer will be limited to home and small business system purchases. However, if customers buy more than 29 systems will be directed to use Microsoft's volume licensing program instead.

HP announced a similar upgrade offer on Thursday and other major computer makers are likely to launch similar offers.