day selection with ajax

The first thing is to change the day selector to a calendar widget. I think it can be much more easier to navigate with that.

The second thing is the changing of the days. Right now, it reloads the full page which is pretty slow.
My idea is a little javascript function, which does the following:
1.) clears all selection
2.) sends an ajax (not ahah) query to get a 2 dimensional array
3.) with 2 nested for loops, you iterate through this array, and check the selected fields