Howtogeek posted a tip about using the Windows Key for the Start Menu in Ubuntu Linux 10.04

Linux distributions like Ubuntu open the main menu with Alt+F1 instead of the Windows key that most new Linux users would be expecting, but it used to be simple to change the shortcut key. Since Ubuntu 9.10 the process isnt so obvious, but we've got the instructions for you.

  Use the Windows Key for the Start Menu in Ubuntu Linux 10.04