Where is a reliable registry key to find install location of Excel 2007?

Question

Where is a reliable registry key to find install location of Excel 2007?

Answer 1

I have found this key to be consistent across all my Office 2007 installations.

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Components\9B905EB838DBFEE4991CF8E66F518BBF]

If you are reading this, and you have Excel 2007, can you Vote this up (or leave a comment) if it is reliable for you too? (Vote it down, or post a comment if it is wrong?)

NOTE: This is not consistent across my machines.

[HKLM\SOFTWARE\Microsoft\Office\X.0\Common\InstallRoot]