What does the bankruptcy of Lehman Bros. and sale of Merrill-Lynch mean for the economy?

Investors may lose billions, does this mean the country is going into another Depression? What can be done, if anything, to prevent another Great Depression? Are you personally hurt by any of the turmoil on Wall Street now, or might you be?? Does it effect you, or could it? How concerned are you about this turmoil, if at all?