Excel SUMIF formula question....please help I'm going crazy trying to figure this out!

Excel 2007 spreadsheet SUMIF formula, need help! This is driving me crazy!!!?
I have an Excel spreadsheet that I need to add up sales within each month.
There are 2 columns, one column with the full date (12/01/09 format) and one with the sale amount. What formula can I use to add up all the December sales?
So far I have: =SUMIF(A1:A3, "12/?/09", B1:B3) I'm just getting stuck on the criteria part to count all the Dec ones.

Here is a simplified version of my data (I have over 2500 sales to total throughout the year)

A B
1 12/01/09 $12.50
2 12/01/09 $5.50
3 12/05/09 $55.50

very simple.

instead of using date as 'formated' date, use it as numeric numbers. excel behaves anything in numbers. once you convert the numbers, bring the year on the left, and insert another function before you actually concatinate (wild card) the year and use the result to apply the same formula.