Run a program from context menu with admin priveledges (vista UAC)
Solution 1:
You can use the Elevate Power Toy from Microsoft and just change your registry key to
[HKEY_CLASSES_ROOT*\shell\Notepad2\command] @="elevate \"C:\Program Files\Notepad2\Notepad2.exe\" \"%1\""
Solution 2:
Use a shortcut to hstart (see this question) with the /ELEVATED parameter to start Notepad2.
[HKEY_CLASSES_ROOT\*\shell\Notepad2\command]
@="\"c:\\path\\to\\hstart.exe\" /elevated \"\"c:\\Program Files\\Notepad2\\Notepad2.exe\" \"%1\"\""