Parents are signing up in record numbers for Florida's prepaid college plan, while similar programs in other states are struggling or closing down. In the first two weeks, more than seven thousand people signed up for fee and dorm plans. Compared with just 284 in the same period last year. Program officials say increasing college costs and a new system of enrolling on line may have sparked the sign-up surge. The plan allows parents to lock in today's costs for tuition, fees and housing for their children.