Change the location of Program Files Directory

Start run from the start menu or press 'windows+R' then type 'regedit' and press enter. Click continue if the the UAC dialog appears.

In regedit Go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion

Find the key called ProgramFilesDir on the right pane

Double click it to modify and now change the path to a specified folder. Click ok and close the registry.

Tip: 
Dont add a '\' on the end of the location, for example c:\program files as opposed to c:\program files\

You can also find Common Files path, Device Driver path, Media Path, Wallpaper directory in this location

For system and special folders use:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders

Note::

Use registry editor carefully. Make a back up of the registry before carrying out any tweaks.