I am a relatively new programmer; a bachelors in CS, about 2 years out of college, working mostly with .NET in C#. I am fairly fluent with SQL interaction/scripting, and have done a little work with ASP.NET (mostly maintaining an existing site).
I'm interested in starting a website in my free time, the closest thing I can describe to it is a social networking site. An extremely friendly UI and communication between the members is very important.
I'm wondering if I should attempt this from scratch via ASP.NET because of my experience with C#, .NET, and SQL Server, or should I try to learn a framework like RoR? or perhaps a CMS like Drupal or Joomla? Really, any direction such as articles, books, etc would be very helpful. Thanks!
Edit: It should be noted I have a Windows Server 2008 machine I was planning on hosting the site from, though it is not absolutely necessary.