Excel 2007
Start
9/4/2008
End
10/28/2008
DRange
=ROW(INDEX($A:$A,Start):INDEX($A:$A,End))
WwSeq
=IF(WEEKDAY(DRange,2)5,0,1)
CntSeq
=ROW(INDEX($A:$A,1):INDEX($A:$A,COUNTA(DRange)))
Count of whole work weeks (Monday-Friday)
Enter with Ctrl+Shift+Enter:
=SUMPRODUCT(--
(FREQUENCY(IF(WwSeq=1,CntSeq),IF(NOT(WwSeq=1),CntS eq))=5))
=7