I love Head First approach...
I have completed Head First Java and now I want to learn Java EE Technologies.. I would like to start by learning JSP and Servlets from "Head First Servlets & JSP"
But I do have access to only the previous edition written for 1.4 Exam...

Can I continue to learn with this book or do I have to start with the 2nd edition of this book written for Java 1.5 

Is there any significant difference between the two editions?
After I complete learning from the book targeted for 1.4, would it no longer be used because of an enhanced functionality introduced with 1.5 !!!

I am not learning to take up any certification exam, trying to learn Java EE technologies...