I try not to change the file extension in Word since I always manage to screw up the formatting. (If your solution works, that would be a good one to add to the Windows Tips Thread TCS started!)
Richard,
I try to avoid using Word altogether

however, ISTR discovering that saving the file as RTF (Rich Text Format) removes all the extraneous material (including all the embarassing change marks that have caught more than a few people out

) You don't change the extension, BTW, you use
File, then
Save As and select RTF (Rich Text Format)
When I get a few minutes, I'll do some tests and if they pan out, I'll post somethin in TCS' thread.