Admitting reluctantly that I actually like the zoom slider in Word 2007, I
wrote this macro that in some ways does even better.
A menu gives you 14 zoom percentage choices, from 25% to 800%
(the program limits). Another choice lets you set any custom percentage.
The macro remembers the last three custom choices you made, and
you can edit the standard choices on the menu.
It also resizes the window to fit the magnification you've chosen, and
sets the fractional/integer character widths for best legibility.
Free in the Files section here, as "Zoom.sit".