You dont need to use Service Locator if you are using Dependency Injection. Both do the same thing ie hiding the complexity of the lookup, and they both do it differently.
You should use one or the other, not both. Read this article -
http://martinfowler.com/articles/injection.html#ServiceLocatorVsDependencyInjection
For your follow-up question, yes, you can use Business Delegate as a separation between the presentation and business layer. There are different opinions on where to show the business delegate component in the Component diagram in part 2. I showed it in the presentation layer.
- Rajiv