Definitely $100 a month because then, you could just buy a laptop with the money plus have extra money!
for me, it would depend on how much money i had. if i had enough to buy the laptop, i would of course buy it, but if i didn't i would try the $100 a month. I think that the best thing to do would be to get a payment plan from hp or dell or toshiba or any other major brand and buy a new laptop, but only pay the 40-80 a month. then you still have a laptop and you aren't dishing out a ton of cash. This question was probably for a bet or something, so i'd rather have a laptop than pay a hundred bucks every month....
I would go for the $100 as in 1 years time of saving you could by a top of the range laptop and then you would still be getting money
I would use the computer in the lab as they are provided for you and many schools charge you a technology fee or a friends computer and take the money.
100/mo in school is going out each weekend, some new clothes, alcohol which can be limited on a student budget.
Your other option is to take the laptop - is it worth more? And sell it :P