client login system, open source

We are building a website in dreamweave cs5.5 We are looking for someone to take our site that will be written with PHP and add a login area for clients and employees. I have basic skills in DW and PHP, so i have worked basic design and layout for the site, however i dont have the skills to add a login area))) We are a private travel company not commercial This login will be much like that of any E-Commerce site i guess Clients can login to be greeted with their photo and see company current news, change there person info, request new service, contact support, book a car/limo via booking calender, review account payments, balance due, and check status of flight or car request. We think it might be just as easy to have a login for our employees also who can view view these sent requests and add notes, search for client accounts if client calls via phone or email. We are OK using open source to keep costs low and development time short . PHPnuke or any other not sure sure how those work and if they fit our need so you will need to have an understanding.