Thanks for your answer. I didn't find the answer to cover the question entierly. So I will be more precis with my information:
The webportal that I'm planing to develop will be a stand-alone portal in ASP.Net MVC. It will communicate with the 4.0 CRM through its API, im not trying to develop a plugin och change any code within the CRM.
Will this be doable in Win server 2008 and Visual Studio 2010 (or 12)?