The version of psinex that is available for download runs only demos. But I have heard that the version that is being worked on, does play some commercial games. No word, though, as to when the next version will be released. Just gotta keep waiting.
I believe Microsoft has a free *viewer* for Excel (.xls files), as they have one for Word.
These viewers only let you view the documents; you can't edit anything. They're free, kinda like Acrobat reader.