You could use a macro that loops through all the worksheets in that workbook.
This basis the count on the number of used rows in column A:
Option Explicit
Sub testme()
dim TotalRows as long
dim wks as worksheet
totalrows = 0
for each wks in activeworkbook.worksheets
totalrows = totalrows + application.counta(wks.range("A:A"))
next wks
msgbox totalrows
End sub
You could replace that msgbox with something like:
worksheets("Somesheetnamehere").range("x99").value = totalrows
Change the name of the worksheet and the address of the cell to what you want.
If you're new to macros:
Debra Dalgleish has some notes how to implement macros here:
http://www.contextures.com/xlvba01.html
David McRitchie has an intro to macros:
http://www.mvps.org/dmcritchie/excel/getstarted.htm
Ron de Bruin's intro to macros:
http://www.rondebruin.nl/code.htm
(General, Regular and Standard modules all describe the same thing.)