The variance in salary for social workers is not big enough to make prestige an important factor in getting your MsW. However, I cannot say that rankings do not matter in the absolute sense. Of course going to U of Chicago (currently #3 MsW program as rated by USNEWS & World) would give you better oppurtunities than going to a local state school for your MsW. However, the the difference in salary is only marginal..so thinking about school costs (and cost of living) should be a more important factor than school ranking imo. Additionally, social work is expected to rise faster than average over the next several years (according to the BLS) so you don't really have to worry too much about finding a job after graduation.