Primary schools can cut their computer costs by nearly half if they stop buying, operating and supporting products from the world's largest software company, government research has found.
Secondaries could slash their information technology overheads by a quarter if they moved away from Microsoft and other commercial programs, according to an analysis carried out by the British Educational Communications and Technology Association.
The findings could undermine the company's hold on the education market.
But they raise the prospect of millions of pounds of savings for schools and the Westminster and Cardiff governments. IT spending in British schools is around pound;1 billion a year.
In a report to be published next week, obtained by The TES, Becta will highlight schools which have turned to free software, which is increasingly becoming available to rival the market-dominating Microsoft Office programs.
Becta, the government's schools' ICT agency, is not naming Microsoft in its analysis. But almost all schools use some of the company's products.
Becta interviewed senior staff at 33 schools which use paid-for software, and compared their overall costs with 15 which have been pioneering the use of free programs and the pared-down hardware which can run them. Average total costs, including hardware and support, were 24 per cent less per computer in secondaries using free software, or open source.
Figures were pound;787 compared to pound;1,036, a saving of pound;19,000 per school, or around pound;60m if all secondaries transferred. In primaries, costs were 44 per cent lower per computer, at pound;692 compared to Pounds 1,228, a saving of pound;13,750 annually for a 250-pupil primary, or roughly pound;220m if all schools transferred.
The report features case studies, including one secondary which spent Pounds 13,000 after scaling down on Microsoft provision for open source. A Microsoft-equivalent set-up would have cost it pound;44,000.
At Orwell high, in Suffolk, deputy head John Osborne said he was able to add 100 extra computers, bringing the total to 280, from the money it had saved after switching to open source.
Microsoft charges schools a licence to run its products. It said that costs could work out at pound;35 a year per computer, which would equate to Pounds 10,000 for a medium-sized secondary with 250 machines.
Advocates of open source say it cuts down on support costs. But open source has caveats: some curriculum software used by teachers will not work on open-source machines and pupils are attached to the Microsoft brand.
Stephen Uden, education relations manager for Microsoft UK, said: "I do not want to speculate about an unpublished report."
He said schools' spending on Microsoft software accounted for only 3 per cent of their total IT spend, and that they only paid a fifth of the rates companies paid to run Microsoft Office.