Path of other program

Hi.
My installer start to install other program (for example Firebird use their installer) and after my installer should to move my files to the Firebird folder. How can i find the current path of other program?
Thanks a lot!

For example Mozilla products write their path to the registry where you can read it.

Thanks.
But how can i get full path (for example user setup SErver Firebird or Client, and path in the registry probably different in that way)
Thanks a lot!