Bristol City Council has dumped Microsoft Office, Corel Word Perfect and Lotus 1-2-3 from 5,000 user desktops as part of a migration to the open source StarOffice 7.
The local authority estimates that the move will save it some £1.4m over the next five years.
The migration was prompted to help meet the government's requirements for improved efficiency in the public sector as set out in the Gershon Review.
According to the council, as well as saving money, the project aims to ensure a more consistent use of software systems across its departments and services where a mixture of products are currently used.
Most of the council's departments will transfer to the new software, although some 1,800 desktops in the city's education service, including schools, will remain on Microsoft Office for the time being.
This is because of the preferential financial terms that Microsoft currently offers for product licences to educational establishments, but has so far not been prepared to extend to other public sector users.
A limited number of other council staff will retain access to Microsoft Office applications where they need to manage the few documents with specific technical features not yet fully supported in StarOffice.
Councillor John Bees, Bristol's executive member for central support services, suggested that the council's decision marks one of the most significant migrations from Microsoft products in the UK.
"This is further evidence that the city council is determined to be as cost effective as it can in the way it works, while neither compromising the quality of its services to the public or the resources available to staff," he said.
"Our IT specialists have spent three years evaluating the options and investigating in detail the technical, financial and cultural issues involved in switching the majority of our desktops to StarOffice. We are convinced that this is the right way forward and will offer benefits all round."
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