This worked for me.  I assume cboSecondary is a LISTBOX (not a combobox) with
the multiselect property set to True

Sub Update_task_part()
' This macro adds the tasks picked in the List Box and adds them to the
' Tasks revenue part of the form
' Created by Christian Simonsen 21/03/06

Dim mRows As Long
Dim i As Long
Dim Msg As String

' hides/unhides the required rows depending on the number of tasks
' picked
mRows = 0
With cboSecondary
For i = 0 To .ListCount - 1
  If .Selected(i) Then mRows = mRows + 1
Next
End With
Range("list_rev").EntireRow.Hidden = False
mRows = 10 - mRows + 1
Range("list_rev").Rows("" & _
 mRows & ":10").EntireRow.Hidden = True


' Gets the task numbers for the rows
 With cboSecondary
     For i = 0 To .ListCount - 1
         If .Selected(i) Then
           Msg = Msg & .List(i) & vbCrLf
        End If
    Next i
 End With

 If Len(Msg) = 0 Then
    Msg = "No items selected"
 Else
    MsgBox Msg
  End If

End Sub