When the rest of the world was busy buying second homes with no money down, MIT professor Andrew Lo was busy beating the drum over a coming financial crisis. For a while, he was playing to an empty room, but now his prescience makes him a voice of authority as we deal with the meltdown and its aftermath. Fortune recently spoke with Lo about the goods and bads of financial reform, how to prepare for calamities to come, and the "holy grail" of good regulation...