The Toronto Star takes a look at a couple of the logistical challenges facing manned missions to Mars.

At the risk of engaging in handwaving, I don't see these two challenges as being all that...well...challenging.
Yes, we do need to find out where the sources of water are, so that we know what will be required to extract them, but with a large power supply it shouldn't be all that difficult to obtain pure, useful, safe water -- by filtration, by distillation, or even (if need be) by electrolysis/combustion. Some form of the latter option will probably be employed on Mars anyway, tainted water or no, to provide propellants for rovers and return vehicles.

As for the food issue, I was pleased to see the scientists cited at the end of the article working on genetically modified organisms to overcome the poor soil and low-light growing conditions on Mars. Though transgenic blue-green algae and veggies grown in untreated urine are not quite what I'd like to see on my menu, at the rate genetic research is progressing I wouldn't be surprised to see the first astronauts on Mars feeding themselves on plants capable of growing in untreated regolith.