Multiple Sites and Mini Sites

I want to create a website that allows users to create their own personalized websites in my system. An example of what I would like to achieve is ewedding.com or weddingwindow.com.

So basically:
1) I register the user
2) They have their own web space - e.g. www.mysite.com/username/homepage/
3) They can add/edit pages
4) Choose different templates

My questions are:
Is this possible with Drupal?
Any suggestions on the modules I will need?