I was hoping someone could help me with a running total question.

I need to keep a running total of hours that someone uses for
disability. Names will always be sorted and together but everyweek
another entry could be made and new names added. I just cannot for the
life of me figure out how to do this. I do not want to use subtotal
because I don't want to add extra rows nor will this work well since
new information is constantly addded.

Column A (Name) Column B (Week Of) Column AC (Hours) Column
AD (Running Total)
Sam 01/01/2012
40 40
Sam 01/08/2012
18 58
Sam 01/15/2012
20 78
Chris 01/15/2012
15 15
Chris 01/22/2012
35 50


Any help is greatly appreciated.

Thanks
Sam