It is one of 40 new languages due to be added, in response to complaints from around the world that youngsters were losing their native tongues.
Microsoft programmes already run in 40 languages including English, Spanish, Arabic and Chinese variants.
A Welsh start menu and some commands will be available in about six months.
Microsoft said it has received complaints from places such as Catalonia, Malaysia and the Arctic regions of Canada.
'Digital divide'
They claim the switch from native languages online is also affecting everyday speech, said BBC North America Business Correspondent Stephen Evans.
Some argue the fewer languages the better for global trade and understanding, but Microsoft is siding with "linguistic diversity", he said.
The other big linguistic groups to benefit from the expansion will be speakers of Gujarati and Tamil in India, of Catalan in Spain, and of Bahasa in Malaysia.
Native languages from Northern Canada and Ethiopia will also be added.
Start menus and instructions like 'save' and 'search' will be introduced, said Microsoft.
The company's worldwide public sector senior vice president Maggie Wilderotter said they were working with governments and academics to develop the languages over the next year, for Microsoft Windows XP and Microsoft Office 2003.
Dato' Hj A Aziz Deraman, of the national language authority of Malaysia, said the availability of Windows in Bahasa would speed up IT literacy and help bridge the "digital divide" between rural and urban areas.
- http://news.bbc.co.uk/1/hi/uk/3522026.stm
Grêt news!
