I\'m a first time iPhone application developer and I\'m developing application for my client who wish to distribute this application to a group of people related to his business
The Enterprise Program is your only viable option for a native iPhone App. Re-read the program details. It's exactly what you want.
If you deploy your App as a Web-App, you can skip this and simply deploy on the company website, so if you don't need native iPhone options, this might also be a viable way to deploy your program.
-t