Ubuntu has a dropdown menu at the top of the screen to launch applications, which is very similar to the way Windows has the start menu at the bottom of the screen. If you are a windows user new to Ubuntu, you may prefer to have the windows key launch the applications menu. Thankfully this is an easy thing to do in Ubuntu.
Go to the System \ Preferences \ Keyboard Shortcuts menu item:
Scroll down till you see the “Show the panel menu” item. Click in the Shortcut column, and when it changes to “New accelerator…”, hit the Windows Key. Click the close button. You’re done!
Now when you hit the windows key, the application menu will pop up. If you hit the right arrow key, you can go to the Places or System menu as well.