One thousand is not a smaill number and penny makes up the constituent parts of dollars, thousands and millions.
This is only a if........
I think I would pick up the one thousand dollars. But I don't think it's worth it to kneel down to pick up the penny compare to his $300 dollars per second (2006 figure). It takes 3-4 seconds to pick up a penny. Would you do that?
On the other hand, if Bill Gates is poor like me, what do you think he will do?