If you are sending text, please send it as plain text, HTML, of necessary PDF.
If you use your favorite word process, slide tool, etc, and send it in that program's format, then you are forcing me install proprietary software on whatever machine I read them on.
Distributing documents in Word format is bad for you and for others. You can't be sure what they will look like if someone views them with a different version of Word; they may not work at all.
Receiving Word attachments is bad for you because they can carry viruses (see http://www.symantec.com/avcenter/venc/data/acro.html). Sending Word attachments is bad for you, because a Word document normally includes hidden information about the author, enabling those in the know to pry into the author's activities (maybe yours). Text that you think you deleted may still be embarrassingly present. See http://www.microsystems.com/Shares_Well.htm for more info.
But above all, sending people Word documents puts pressure on them to use Microsoft software and helps to deny them any other choice. In effect, you become a buttress of the Microsoft monopoly. This pressure is a major obstacle to the broader adoption of free software. Would you please reconsider the use of Word format for communication with other people?
Converting the file to HTML is simple. Open the document, click on File, then Save As, and in the Save As Type strip box at the bottom of the box, choose HTML Document or Web Page. Then choose Save. You can then attach the new HTML document instead of your Word document. Note that versions of Word change in inconsistent ways -- if you see slightly different menu item names, please try them.
To convert to plain text is almost the same -- instead of HTML Document, choose Text Only or Text Document as the Save As Type.