Bad idea. Word is a proprietary product. Not only the customers will have to pay for the license, there would be a vendor lock-in (
http://en.wikipedia.org/wiki/Vendor_lock-in[
^]) on the product, no compatibility, nothing good.
Think about: 1) HTML; 2)
System.Windows.Forms.RichTextBox
; 3)
System.Windows.Controls.RichTextBox
; 4) WPF Flow Document; 5) something else.
Please see:
http://msdn.microsoft.com/en-us/library/system.windows.forms.richtextbox.aspx[
^],
http://msdn.microsoft.com/en-us/library/system.windows.controls.richtextbox.aspx[
^],
http://msdn.microsoft.com/en-us/library/aa970909.aspx[
^].
[EDIT]
At the same time, Word file format compatibility is the easier problem. After all, OpenOffice, LibreOffice and other products support all versions of the format, please see:
http://en.wikipedia.org/wiki/OpenOffice.org[
^],
http://en.wikipedia.org/wiki/LibreOffice[
^].
If you would like to support only the newer Office Open XML, the format itself is available and is standardized under ECMA-376 and ISO/IEC 29500:2008:
http://en.wikipedia.org/wiki/Office_Open_XML[
^],
http://en.wikipedia.org/wiki/Office_Open_XML_software[
^].
Please see the comparison chart on Office Open XML software:
http://en.wikipedia.org/wiki/Comparison_of_Office_Open_XML_software[
^].
As some source code is available and open, you can use it.
—SA