I'm not sure, but I bet they give them out during orientation.
They probably won't mail them to you before because that would get really expensive.
Also, they don't give it to you- you pay the rent for it with your tuition (can't give it to you because of some legal mumbo jumbo), then they sell it to you at graduation for $1 or something like that.
You could always call the admissions office just to double check when you recieve the laptop.
And from what I understand, they have an extremely competent IT dept. which could probably upgrade it for you for cheap. But I don't know if they will let you upgrade it because technically its not yours. But I believe you can do whatever you want with the software on the thing (music, add programs, etc.)