For Office 2007 you can download Portuguese Language Pack for either Brazil
or Portugal from the Office web site. Go to the Office web site
http://office.microsoft.com/en-us/default.aspx and enter "Language Pack" in
the search box. It is a download purchase for $24.95 for each language, in
the US. For 2000-2003 you could buy the appropriate Proofing Tools CD,
which has 50+ languages available. I do not know whether you need the same
version as your Office in that case. These are hard to find now, but
possible.
http://buy1.trymicrosoftoffice.com/buyus/product.aspx?family=langpack&culture=en-US
Portuguese is listed under "Brazilian Portuguese" and "Portuguese" for
peninsular. The 2007 Language Packs do not appear to be compatible with
earlier versions of Office. You can also change the interface language from
English to Portuguese. If you don't know the Portuguese computer jargon,
this can be confusing.
Saúde,
Earle