=SUMPRODUCT(--(A1:A1000="Stewart"),--(G1:G1000="Fiduciary"),C1:C1000)
Note the double unary operator (–), used to coerce Logicals to Integer (True = 1, False = 0)
Also note: sumproduct does NOT work with entire columns (eg. use A2:A2000 instead of A:A)
Source: Excelforum.com