VBA to calculate hours between 2 date/time excluding saturday & sunday

I need to calculate hours between a start date/time and an end date/time excluding saturday & sunday hours.
The start may possibly start on a saturday or sunday and the end may possibly end on a saturday or sunday.
But i only want the sum of weekday hours elapsed.

eg 3/jun/2011 11:00:00 am to 8/jun/2011 9:00:00 am would = 70 hours
eg 4/jun/2011 11:00:00 am to 8/jun/2011 9:00:00 am would = 57 hours
eg 3/jun/2011 11:00:00 am to 5/jun/2011 9:00:00 am would = 13 hours

Any help would be appreciated