(I went to Uni' in Wales, so I feel duty bound to publicise this for my Welsh-speaking friends!)
Microsoft have worked with the Welsh Language Board to develop two new Welsh-language interface packs - one for Windows XP and another for Office 2003. They are free to download, and enable Welsh speakers to work more easily in their chosen language whether at home, in business or in education.
To find out more, visit the Welsh pages on the Microsoft UK website.