Adding numbers between know dates

I need an Excel formula that will add a column of numbers by the date in which they (each number) occurred. The dates and numbers in sequence (which helps). For example, to add all of the monthly payments (by month) that will occur between 10/1/04 and 10/1/05 (in this case one payment per month) what could I use as a formula?

Help would be appreciated as Hurricane Francis blows right over my head here in Orlando.

 

Here ya go: http://www.dicks-blog.com/excel/2004/03/sumif_between_t.html