Excel 2007 : Timesheets

Help please...

I have to create a timesheet that will automatically work out my hours of work, based on the following. Monday to Thursday basic staff hours are 08:00 to 16:30, with a 30 minute unpaid lunch break and Friday is 08:00 to 13:00.
The total standard hours worked in a week is therefore 37.00

Any overtime that is between 06:00 and 20:30 should be calculated as x 1.25 and between 20:30 and 06:00 should be calculated as x 1.33. The only restriction here is that the standard hours have to equal 37.00 before any overtime can be earned at the applicable rate.

I have formulas that work out overtime as a standard flat rate (i.e. x 1.00), when the hours for that day are over 8.00, but cannot work out how to sort out a formula that calculates differences between 1.25 and 1.33 situations, as seen on the attached example for Tuesday.

What I need is to have a formula that calculates these two different amounts of overtime as long as the standard hours are equal to or greater that 37.00 i.e. what has been manually calculated in columns I and J.

Can anyone help me please as this is driving me crazy ;-)