legally no where. You can try open office which is another companies attempt at making a free office alternative and is compatible with ms office files (make sure when you save you choose the right file format). Your only other option is to see if you can get a student deal or something on office.
Xbox GT: Zarosian 3DS ID: 1848-2118-1570 Origin and SteamID: Zarosio
Actually OpenOffice is a direct descendant of StarOffice which predates MS Office by a good half decade. Personally I'd go with the more featured LibreOffice fork though, assuming the MSDN through work/school isn't an option.