My main concern for you entering the nursing profession at this time is - there is a GLUT of new graduate RN's. It is especially competitive to get into the more lucrative areas such as OB, ER, OR PEDS,ect and in some locales hospitals will NOT hire new graduate RN's at all.
In response to the perceived 'nursing shortage' nursing schools have been churning out far more nurses than the health care employers want to hire. Sure, they still want nurses who already have experience but they don't like having to orient new grads if they don't have to. Due to the economy, experienced RN's are coming out of retirement or delaying it - thereby the applicant pool is full of more qualified nurses so they often will not even consider a new graduate.
This will change someday because the RN workforce is aging (according to the studies I have seen) but I don't predict any change to the job market for at least 5 years - if anything it will get harder.
I would go with the ultrasound job. You might just be in demand since there aren't as many schools for ultrasound techs. I doubt you would have any more difficulty getting a job for that than nursing. Check into it for yourself. Practically every ABC community college in America (in addition to universities and private schools) is now producing a class of nurses 1x or 2x a year. Many of these programs have popped up in the past 5 yrs or so and I have read about more schools trying to start nursing schools.
It is too bad that nursing is sugar coated by the news media the way it is. Some jobs are okay, but there are alot of them that you don't want no matter how much the pay might be due to dangerous working conditions, unreasonable work assignments, out of touch and punitive managers who only care about the $$$.