Click on Start | Control Panel | Regional & Language
Options | Languages tab | Details | Settings tab | Default input
language: <choose your language> | OK.
Open a new or existing document. Press Ctrl+A to select all of
the text. Click on Tools | Language | Set Language | <choose
your language> | uncheck the "Detect language automatically" and
"Do not check spelling or grammar" boxes | Default | OK.
If you are prompted to save changes to your Normal.dot global
template when you close Word, say yes.