What's the best machine for development?

What specific reasons are there for assembling an entire software development environment on a local machine?

• As a general rule, each software development project requires team members to configure their machine to be able to develop. When you are working on projects and contracts where there are either a lot of team members, or a lot of changing team members there starts to become quite a cost to having and helping individuals to set up a complete development environment. The point which is unclear is whether every developer needs the whole environment or if the team is better served having staging servers which allow the database, or portions of the server stack to stand alone. Depending on the situation this question has different answers. Lets assume, for this question there is a Coldfusion, IIS, SQL, and MongoDB server side and a Flex/HTML/CSS front end for development of a replacement for a high volume ECommerce Site.

• Answer:

  To be productive, developers are going to need access to instances of the environment that they can modify and in many cases, simply break.  If they have to share instances, it is very likely that they will collide and get in each other's way.