"Now it is preparing to take part, alongside BT, and Cisco Systems, in the electronic health record project, nicknamed "Project Lightbulb".
There is likely to be some disquiet among enthusiasts for electronic health records - who would prefer that a commercial company did not "own" the source code for whichever system is adopted.
Dr Adrian Midgley, a primary care computing expert, said: "What we will get with Microsoft is a three-year lease on a health record we need to keep for 100 years."
