controls - A dialog to set up working hours

I've got a dialog that helps an user to set up working hours for different days in a week. In this dialog an user can choose a day of week and hours/minutes which point on start/end of working time, e.g. "Mon 9:30 - Mon 16:00", "Fri 21:00 - Sat 04:30", etc.

I've already got such dialog which works properly, but users ask to improve the dialog design to simplify (and make more comfortable) their work with the dialog.

I've decided to begin with the following question here: Is there any product which has similar dialogs to solve a similar task effectively? I could start learning from existing solutions. Could anyone please tell me names or links to such products?

UPDATE. This is the dialog looks like at the moment. It looks ugly a bit :) But I have no idea what I need to start with and where I need to go. Could anyone please advise any improvements?

The controls are (from top to bottom):

1. A drop-down list and "X" button. A list of user-defined presets. "24/5" is a name of the current preset. "X" button deletes the current preset. To insert a new one just type another name at the drop-down list area.



2. Time pickers with spin buttons. It sets up start/end time.


3. Buttons "Update", "Insert", "Delete". Updates/deletes an item selected in the list box below. The Insert button is enabled in case the list box below doesn't contain start/end time which the time pickers currently contain.


4. A list box. A list of start/end time inserted by an user into the current preset.

Answer

We got a page like that in a server admin interface. You can unfortunately not download a demo of it (as it is the server admin interface) but it looks kind of like this:

^{download bmml source – Wireframes created with Balsamiq Mockups}

One of those bars each for every day of the week. And then a set of presets like "Always", "Never", "Working hours", and so on.

EDIT:

In this case the draggable handles is the only input with discrete steps each 15 or even 30 minutes. The bar can also be split into several bars, allowing for multiple intervals during the same day; and rejoined by dragging two bar handles to overlap.

Oh, and all cred to our amazing designer, not me, of course. :)