If money is not a problem, definitely purchase through ND's computer store. I was a physics-in-medicine major and used a PC. Mac's are definitely faster at running particle simulations, but unless your daughter is going to be doing hardcore research in physics or engineering a PC will be fine. Recommendations for this fall can be found:
Get the Right Computer - Office of Information Technologies - University of Notre Dame. In most classes a laptop is not required, but I found it to be extremely useful in instances were notetaking is a must (profs don't hand out notes). Typing is much faster than writing and it was easier for me to actually pay attention to the material the professor presented instead of just worrying if I wrote down everything.