Here's a quick exercise to illustrate some of the differences:

Put these values in A1:C5
Name____Amount1__Amount2
Alpha___100______10
Bravo___200______20
Charlie_300______30
Delta___400______40

Now try these formulas:
E1: =SUMPRODUCT(--(A1:A5="Bravo"),B1:B5)......One Amount col
E2: =SUMPRODUCT(--(A1:A5="Bravo"),B1:C5)......Two Amount cols
E3: =SUMPRODUCT((A1:A5="Bravo")*B1:C5)......Incl. heading row
E4: =SUMPRODUCT((A2:A5="Bravo")*B2:C5).....Excl. heading row

Does that help?
Post back if you have more questions.
--------------------------

Regards,

Ron
Microsoft MVP (Excel)
(XL2003, Win XP)


"Kevin" wrote in message
...
I have been doing a lot of reading on this function and can usually get it
to
work to do the job - not overly complex.
One thing that is still not understood (and not the only thing) is what is
the difference between using * or , to separate the arrays in the
argument?

Kevin