The bane (correction: “one of the banes”) of the new opus of the Microsoft Office saga (MS-Office 2007) is that the Redmond developpers once again changed the file formats. I’m sure that this is for the best. But if you went the MS-Office 2007 path and not your colleagues or friends, they no longer can read your files.
Solution (partial because you still need to do something): Crunch all documents through a software to make them readable. This is basically the offer from Docx2RTF, Windows utility that you can download freely.