Lib - if we were to raise living standards of everyone on the planet to the European average, we'd need 6 Earths to support them all (or something like that - can't remember the exact figures). True, solving distribution and sharing problems would go a long way to solving current problems, but it wouldn't be enough. However, it is posible to re-distribute resources so that everyone gets a fair share, and a good standard of living. However, that isn't possible, what with people being greedy bastards.
As for the 120-year span thing, that sounds like a reasonable time. If everybody lived properly healthily, and didn't muck about with their bodies, they could easily reach 100 and beyond.
(NB: the "hundreds of thousands dying" thing refers to all deaths on the planet, not just early or unnatural ones)