Count months in a range of cells

I have a what seems to be simple problem.

I have names in column C and dates in column D
Example

Lee 5/15/2010
lee 5/17/2010
lee 6/2/2010
lee 7/10/2010
lee 10/5/2010
jones 3/2/2010
jones 5/25/2010
jones 6/10/2010
jones 6/30/2010
jones 8/10/2010


I want a forumula that will tell me how many units were sold in MAY for LEE
how many units were sold in June for Jones
??? make sense?

I have about 40 different names with over 2000 rows of results so if i can just get the formula for one, I might be able to handle the rest..