Tesco.com has officially switched to Microsoft's Windows Server 2003 platform, becoming one of the system's first users.
Tesco.com has moved to the new platform to cope with the growing scale of its operations.
Tesco.com head of operations and infrastructure Mike Yorwerth said: 'Our existing infrastructure was perfectly adequate for running the business, but could prevent us from taking advantage of new opportunities and support for further growth in the future.'
Over Christmas, Tesco.com Web servers were approaching full capacity, and any increase in demand caused customers problems.
Tesco.com turnover is about£450 million a year and the business is now making a profit.