First I should say that Super brings up the big overlay grid, that is called the Dash. Tappipng Alt brings up the HUD, a smaller text field in the top left. It's a 'type-a-little' interface to all the commands in system and application menus. We can get a link for more info, if needed.
So you can shut off the Super key, with the low-level tool Compiz Config Settings Manager. The package name is compizconfig-settings-manager, if it's not installed yet.Open the Dash, and type 'ccsm'. You should see an icon you can run. When the app opens, you may get a warning that it's a tool that can mess up your system. This is true; it doesn't have any constraints on choosing settings that may break your desktop in different ways. But this change alone will be ok.
In CCSM, find and choose 'Ubuntu Unity Plugin'. The first tab, Behavior, should have an item 'Key to show the launcher'. Click on the button that shows Super, and you can disable it, or choose a different key if you want to try that.
- this is how it looks for me under 12.10. It's about the same, as I recall, under 12.04.
- It should probably say 'Key to show the dash'. Maybe I'll find or file a bug about that.
- unchecking 'Enable Ubuntu Unity Plugin', under Unity, is the kind of thing that would send your window controls, and lots of the UI, into never-never land.