I posted this before, but no-one appears to have noticed ;-)
You can use VB to give you an on-top pop-up:
You need to put this under 'ThisOutlookSession' and sign it with a digital certificate (plenty of info elsewhere on how to do that)
Private Sub Application_Reminder(ByVal Item As Object)
If TypeOf Item Is AppointmentItem Then
MsgBox "There's a reminder! Click OK to see it", vbSystemModal, "Dude!"
I admit it's not an elegant solution, but if you need something to be all up in you face about meetings, then this will do it.