Re: SUMIFS and WEEKNUM
Quote from NBVC;670204=SUMPRODUCT(--(WEEKNUM(Sheet1!$E$2:$E$100)=A8),Sheet1!$H$2:$H$100)
I don't believe that formula will work (certainly not in Excel 2007) because WEEKNUM function can't handle ranges - in Excel 2007 and later, though, it can handle arrays so you can use +0 to convert like this:
=SUMPRODUCT(--(WEEKNUM(Sheet1!$E$2:$E$100+0)=A8),Sheet1!$H$2:$H$100)