Merrill Lynch is a global powerhouse that combines immense distribution capability with a breadth of product offerings for all kinds of clients-from its faithful Main Street customers to foreign governments and huge institutions. But a behemoth only remains one if it can respond to a changing marketplace. With an aggressive leader at its helm, today's Merrill Lynch seems determined to do just that. Merrill's strong position on Wall Street has made it a coveted employer, and competition for jobs