English, Windows 8.1,
I have been using MS Word 2003 for many years. I do simple Word docs. and Excel docs. Can you advise which version of Libreoffice to download?
In recent versions of LibreOffice docx/xlsx/pptx have gotten more attention than the binary formats, so the compatibility for doc/xls should roughly be the same.
I’d probably go with the older ‘stable’ version.
I would advice to use LibreOffice 4.2 it is according to my experience quite stable. But what ever version you use I strongly suggest to save files in ODF file type by default to not lose the data. Only save to Microsoft format when you first already saved in ODF format.