Count data in adjacent cell if criteria met

[aim2012]

I want to count the value in a adjacent cell if certain criteria is met....

so
01/08 02/08
detail Hours Detail Hours
Person A W/D 7.5 OT/P 4
Person B SICK 5 Hol 9

I want to be able to add up all Person A's W/D hours for the month and all their OT/P, SICK, Hol etc in separate summery cells.
And I want to be able to do this separately for each person.

Thanks for any help