Welcome to the Board
If as implied you're using XL2007 you can use SUMIFS
of course the tests can be replaced with cell references
Pending other requirements you might find a Pivot Table would also work for you (see link in sig. for general intro.)
Prior to XL2007 you would be looking at using SUMPRODUCT which would not accept entire column references and is inefficient - so best to keep precedent ranges as small as possible:
on a final note please try to keep titles related to the specifics of the problem - I've modified for you on this occasion
thanks
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