Tom,
First go to Tools/Options/Schedule tab and set the Duration for "weeks".
Then if the file already has existing tasks whose Duration is shown in
days, run the following macro to make the change.
Sub DayToWk()
For Each t In ActiveProject.Tasks
If Not t Is Nothing Then
If t.Summary = False Then t.Duration = t.Duration / 2400 & "wks"
End If
Next t
End Sub
Once the option has been set and existing tasks have been converted any
new tasks entered will have a Duration of weeks.
Hope this helps.
John