I was a volunteer EMT for about ten years before starting nursing school. I am now a graduate nurse getting ready to take the NCLEX exam for RN. Being an EMT helped me to a point - it helped on test questions regarding prioritization and ABC's.
However, nursing is not even remotely like EMS. Apples and oranges are both types of fruit, but are two totally different kinds of fruit. In the same way, EMS and nursing both involve patient care - but involve two totally different types of patient care. EMS is fast paced, you will get bored with having to learn to do bedpans, bedbaths, and ambulating elderly patients. Yet, there is a tremendous (and often scary) amount of accountability and responsibility with nursing. Much of nursing revolves around medicines. You will have to learn about giving drugs to a far greater degree than a paramedic: there are more of them with far more numerous nursing implications.
More than than, nursing involves the ability to critically think (problem solve) your way through situations in a way that EMS never does. NCLEX test questions assume you know the content (think - a dozen nursing textbooks, some of them five inches thick!) - it tests your ability to think on your feet, And yes, to a certain extent, EMS does the same thing - but not nearly to the degree that nursing does.
You will have some advantage though, in areas of critical care and ABC's. I found it to be a mistaken assumption, however, that because I was an EMT, it would really help me in nursing school. For me, that was not the case. There were also CNA's, LPN's, OR techs, paramedics, respiratory therapists, and others who had degrees in Biology (one taught Biology at a major university) in my nursing class. I was just one of many with various healthcare backgrounds and we were all in the same boat trying to make it.
My two cents worth - Denise