Windows Vista / Windows 7: Enable Display of Letters for Keyboard Navigation
In Windows XP, the Display control panel had an option that let you unhide the shortcuts for keyboard navigation.

If you deselect the option that hides the keyboard navigation letters, then you see underlined letters in the menus and on buttons, that indicate which key you should press along with the Alt key to make something happen. Like File, Edit, and View. In previous versions of windows, these shortcuts were always displayed.
If the option to hide these shortcuts is enabled, you have to press the “Alt” key before they appear.
The option to unhide the keyboard shortcuts was removed from the GUI in Windows Vista. But, you can still enable it in the registry.
Open regedit and navigate to:
HKEY_CURRENT_USER\Control Panel\Desktop
Here, on the right, find the “UserPreferencesMask” value. It has a series of hex numbers as the data. You need to change the first one from “9E” to “BE.” Because of the way the registry editor works, you’ll have to insert the “BE” at the beginning and then delete the “9E.”

After that is done, log out and log back in. You should now have your keyboard shortcuts displayed by default.

This also works in Windows 7.