How does Walmart keep its prices so low? The so-called guest workers from Mexico who peel crawfish at a Louisiana seafood supplier for Wal-Mart know: They are locked inside the plant, forced to work 24-hour shifts, cursed and threatened with beatings by shovel if they fail to make their quota, and endure  constant surveillance at their nearby trailers from a boss who warns them, "You don’t want to know me as an enemy." Having gone on strike from C.J.’s Seafood and filed federal complaints, they head to New York today to protest Wal-Mart, its subsidiaries and related boards - including Goldman Sachs - at their corporate headquarters and homes. Brought to you by the feisty National Guestworker Alliance.