We are looking to create and develop a Web-Based CRM/CMS system that will be module based. 

We are looking for input on the best way to build a module-based solution... such as PHP, .Net, Java, etc...

If you have created a module based solution before please send sample work you have done or any demo's.

The solution will be a simple CRM/CMS solution with basic features and then have the ability to activate other modules such as live chat, e-commerece, billing/invoicing, email marketing, etc...

We are looking to own the technology and would not want to use opensource.