I would go with the D50, simply becuse it is a good reliable camera, or at least, mine is. It can use older lenses.
For a student, maybe the D40 with the (18-55 no VR) lens epoxied in place forever! And, the Program dial glued on AUTO!
Of COURSE your student is a marvelous and wonderful human being...a star among their peers...but...I always cringe when somebody wants to buy their college student a camera.
Those cameras wiil be bashed, stuffed into purses,drawers, glove boxes, gym bags with wet, dirty socks and rhyming items, ignored, put away wet, with fingerprints on the lens, and generally have the merry Aitch beaten out of them!
Surprisingly, many do survive this! But, a rugged and inexpen$ive point and shoot seems like a wiser investment...it'll cost less to replace when (not if)it is stolen. Buy a pink one...somebody would have to be really desperate to steal one of those!