Oren has one of the best one liners about the benefits of Inversion Of Control Containers in a project in this post:

"Other people on my team keep adding components, and they aren't even aware that they have IoC there. They just know that if they put the IFooService in the ctor, they will get it when the code is running. And if they add IBarService and BarServiceImpl, they will be available to any component that uses them."

Here's a quick "Getting Started" if you've never seen this before, using the Castle Windsor Container Framework for .NET.