The newer .docx format, which is based on the new open format XML language, compresses documents when saving them, which might account for the difference in saving. You would need to provide more info respecting the .doc files. Were they created with 2003 or 2007? When you created them, before saving, were they .docx or did you open Word, save as .doc, and then enter your data in the document? I'm guessing that the compression is at work somehow, from origination.