Volunteer Vs. Work

Let me set up the scenario for a sec.
I am a non-traditional student in a post-bac program at drexel college of medicine. (was a philosophy major at a fairly prominent liberal arts college)

Since I graduated in 2004, I worked for the Red Cross as a phlebotomist at blood drives for a year and a half.

I have since moved to philadelphia for the post-bac program, and been working full-time at a major hospital (Thomas Jefferson Univ. Hosp.) as a tech in the blood donor center there. I screen blood donors, preform health histories, take physical findings, draw blood from donors, and preform first line processing of blood. I also preform therapeutic phlebotomies and apheresis (plasma exchanges, platelet/WBC depletions, collect Stem Cells for transplant) on both inpatients and outpatients with the hospital. I also regularly attend rounds and get a great deal of experience with pathologists, hematologists and oncologists.

Basically my question is this; I have a year left in my post-bac program, should I continue with this job, or do I need to volunteer? In other words, is it the health care experience that allo med schools are looking for or is it the fact that you volunteer? Unfortunatly with full-time job and part-time school I don't have time for volunteering and I am wondering if I need to make time.

Any insight would be great.