Linux: Remap the menu key as a secondary windows key

My MS Natural Ergonomic Keyboard 4000 died after seven years of use — the underscore key stopped working. So I ordered a Microsoft Ergonomic Keyboard LXM-00001 to replace it, and found that the menu key is in the WRONG PLACE. It gets frustrating to hit the menu key when I actually wanted the windows key.

How to solve? Edit /usr/share/X11/xkb/symbols/pc and replace this
key <MENU> { [ Menu ] };

with this
key <MENU> { [ Super_L ] };

And restart the computer.

Originally, I tried a solution where I used xmodmap to remap the key at login time, but it wasn’t reliable and didn’t work across laptop sleeps. Editing the file in /etc works better.