If you have the values of the waveform (say from theoretical analysis) you could use excel to create a graph. The excel graph is embeddable in Word.
I use matlab or spice to draw the waveforms, then I just print screen them and paste them in my document.
I generally make artwork in powerpoint using primitive shapes (lines, boxes, etc), and those can be imported into other office programs. Not very efficient but the results look nice.