Hello garryshape,
if you have the Language Packs installed for any language, you can mark one or more paragraphs to a specific proofing language. Highlight the paragraphs, click the Review riboon, then the Language icon and set the proofing language. With the appropriate Language Pack installed, the spell check will then apply for that language.
You can download language packs and updates directly from Microsoft.
http://www.microsoft.com/downloads/details.aspx?FamilyId=1F5C7D10-B4F9-482D-B0E5-9547A7F508E5&displaylang=encheers, teylyn