I agree with dp. The author of that screencast even says that you should roll your. This is so you will know how they work. Then once you have that down you can move on to the more full featured one's.
It has also been mentioned that there really isn't that a 'one IOC container to rule them all'. This is because they pretty much all have the same features. It comes down to which implementation you favor. For instance, if you are using the Enterprise Library Framework then heavily then you might favor the Unity container because you get free tie-ins to the rest of EntLib. Or maybe you are allergic to XML then you can use Ninject which has a very nice fluent interface. Each framework has its strengths and weaknesses but they will pretty much be the same from the beginners stand point.
