You don't need to modify Registration.ini to modify that info though, you can change that from the Settings program too. I guess it's good to know where the files are though in case you want to get rid of the game settings if you're using the non-portable game.
Note that the folder names are different depending on operating system as well as language settings. Judging by the paths you give, you must be using Vista or 7, but on XP you'll find the files in a different location.