Date/Time Difference

I have a table containing following Columns plus other columns:
Start Date 04-01-2002(mm-dd-yyyy) varchar(10)
Start Time column 09:30:30(hh:mm:ss) varchar(8)
End Date 04-05-2002(mm-dd-yyyy) varchar(10)
End Time column 09:45:30(hh:mm:ss) varchar(8)


1]We want to create a view for Report Users So that they could just select
the other columns and difference in start Date/time to End Date /Time.
2]The Difference in time should be based on Business Day. i.e.
Saturday & Sunday should be excluded. &
3]Each business day is defined as 8.00 am to 5 .00pm
( 1 Business day = 9 hrs)
4]The time is stored as 24 hour clock.

For e.g.
Start Date Start TimeEnd Date End Time Desired Output
04/01/2002 10:00:0004/01/2002 3:30:00 0 Days 5:30 Hrs
04/01/2002 16:00:0004/02/2002 10:45:00 0 Days 3:45 Hrs
04/01/2002 09:00:0004/03/2002 10:45:00 2 Days 1:45 Hrs
04/05/2002 16:30:0004/08/2002 9:45:00 0 Days 2:15 Hrs******
******In last case as 04/06/2002 & 04/07/2002 were Saturday & Sunday ,hence
excluded.So the difference of time is just 2:15 hrs


Can you please give me a suggestion/pseudo code/logic on how I might do this?
We cannot use cursors as we want to make a view.This is for SQL Server 2000