ExcelBanter - Pivot Table Filter Formula

I have a set of payroll data that I need to put into a pivot table, do some
calculations, and filter but I can't figure it out. Here is what I have:
Name Date Hours
John Doe 1/1/10 10
John Doe 1/2/10 8
Jane Doe 1/1/10 9
and so on
I want to summarize this data by week (can use the weeknum formula) and only
report people who work a certain number of hours a week. So my pivot table
needs to look like this (assume I only want to see people working 50 hours)

Name Week Number Total Hours(using pivot to calc)
John Doe 1 60
3 55
Total 195

Note that I want the total to be all the hours, not just the ones 50.

Seems like I could do this if I could filter the value field.
Any help would be greatly appreciated.