i'm using the following formula to count the number of times a certain value
appears in column A when the value in column B=Dave. I want to adjust this
formula so that it counts the number of times a certain value appears in
column A when the value in column B 'contains' the string Dave. Cells in
column B may contain something like Dave Smith (not just Dave).

=SUMPRODUCT(--(A1:A100=C5),--(B1:B100="Dave"))

Thanks in advance.
Excel 2003.