Depends on the type of cardio your doing I think. If your doing easy cardio like walking/slow jogging then its not really going to do anything to hurt you. I think this debate is more of just a warm up thing and it probally won't hurt your workout in my opinion. That being said, alot of people don't even warm up before lifting, me included, so its all your preference. I personally do HIT (high intensity training) for my cardio and since its pretty strenuous I focus on cardio during the off days. Doing cardio on your off weight training days also gives you something to do on those days and besides watching Arnold movies
Lots of good opinions on this though..might want to check on some of the bigger boards like Steroidology or Elitefitness.