Can Excel 2003 do this? Field Calculation in Pivot Table

Afternoon all, Pivot table novice here.

I am working on a large pivot and want to add a field WITHIN the Pivot.

I am currently returning these fields, cut by year in the row area and the data is cut several different ways across the column area

Count of Work Order Number
Sum of Total Day time
Sum of Total OT
Count of Total Day time
Count of Total OT
Sum of Travel Hrs

What I want to do is add a new field which will show the sum of Total Day time averaged across all the Non - OT lines on the report so the formula would be (Sum of Total Day Time)/(Count of Work Order Number-Count of Total OT).

I'm aware that Excel 2003 may not be able to do this but I would like to know.

If it is definitely not possible in 2003 then can you tell me how to do it in 2010 (if possible) as I have that on my home PC. It means much shifting around of data but I could do it that way.
If it's not possible at all then still let me know so I can stop gnashing my teeth and staring at it and get on with my life.

Cheers,
Carysfoj

Like this? http://www.contextures.com/excel-piv...ted-field.html

Thanks. I used the script below but it gave me the sum of total day time divided by the SUM of the workorder numbers less the SUM of but I need to use count on the

=('Total Day time' )/('Work Order Number' -'Total OT' ) and the answer comes out as zero.

Below is a snapshot of the pivot with our field as field2
The real Value should be 1.08 (596.47/(605-54)

Data OPS
Count of Work Order Number 605.00
Sum of Total Day time2 596.47
Sum of Total OT2 106.70
Count of Total Day time 511.00
Count of Total OT 54.00
Sum of Travel Hrs 174.00
Sum of Field2 0.00

I think you need to upload a workbook with your sample data, a pivot table and the numbers that you want.

That way we can have a look at what you're actually trying to do