Quote Originally Posted by eadz
In your KDE control panel under Regional & Accessibility -> Keyboard Shortcuts

you can use the windows key in combinations, e.g. Win+z.

I'm not sure how to make it pop up the "start" menu like in windows..
I use that exact shortcut combination to popup the menu, when opening the Keyboard shortcuts look for the Panel option then Popup Launch Menu and add a combination as the alternative to the already existing ALT + F1 that is there. You could try using it as a single key but I recall having problems with it not wanting to add a single key it wanted combinations.