I need to sum a column of numbers in cells B1 - B5 from the range in Column A
from a date greater than the one in cell C1. How do I do this?

Example

A1 = 01/01/2007 B1 = 13 C1 = 20/02/2007
A2 = 01/02/2007 B2 = 4
A3 = 01/03/2007 B3 = 9
A4 = 01/04/2007 B4 = 31
A5 = 01/05/2007 B5 = 6

In this example, the sum total would be 46. How would I write that as a
formula? Would the sum total update if I changed the C1 date?