I'm a fan of xp methodology, and I am studying and using it a little at a time. 
  
One of the questions I do to myself in these days is:
    - What is the difference between SCRUM and XP? 
I have found some answers in Martin's article: 
http://martinfowler.com/articles/newMethodology.html 
How Martin wrote the big difference are: 
    - Scrum concentrates on the management aspects of software development 
- Scrum dividing development into thirty day iterations (called 
 'sprints') and applying closer monitoring and control with daily scrum
 meetings
- Scrum places much less emphasis on engineering practices 
 
I still prefer XP because I like the TDD approach. 
What do you think about?