Even in XP there are things you need up front. These include:
Appropriate tools to the problem domain.
A team skilled with those, and willing and able to go XP.
Customers willing to commit time to their involvement in the process.
Star Unit and an SCM appropriate for your tools.
At least one satisfactory Spike Solution.
An initial Commitment Schedule full of User Stories.
All these things are architectural.
See original on c2.com 