The university would probably be losing more with you mining than you would make in income. CPUs won't earn anything significant, and GPUs will lose usefulness (rather, cost way more to run than what they'd earn BTC mining) when/if ASICs ever arrive (currently 2-3 months behind delivery dates, and bankruptcy very possible for one of the manufacturers).
However, at least poclbm, phoenix and guiminer have Mac compatibility (no idea on others). For GPU card comparison in general in relation to mining, see
https://en.bitcoin.it/wiki/Mining_hardware_comparison - best $/MHs will depend on what you buy the cards at, but 5xxx GPUs are generally best $/MHs (58xx series used to almost always be best $/MHs, but unsure now), with the 7xxx series having best $/Wh numbers.