On windows machines, what registry keys can i look at to determine if Firefox is installed? So far I've been looking for HKLM\Software\Mozilla\Firefox but have just found a user's machine where that key doesn't exist but they have firefox. It seems they have firefox installed to C:\Users\xxx rather than Program Files so I'm assuming there's a way for non-admin users to install it only into their User section, and the installer only writes to HKCU section of the registry. In this user's case there were HKCU registry entries like this, among others:

[HKEY_CURRENT_USER\Software\Mozilla\Mozilla Firefox\31.0 (x86 en-US)\Main] "Install Directory"="C:\\Users\\ausername\\AppData\\Local\\Mozilla Firefox" "PathToExe"="C:\\Users\\ausername\\AppData\\Local\\Mozilla Firefox\\firefox.exe"