Form validation before submission to ASP page

I have a timesheet type form that has 40 different row - each row has two dropdowns, one for a project and one for a task, and a dropdown box for each day of the week. Once a project and task has been selected, hours spent on that task each day of the week are entered into the text boxes.

What I would ideally like to do is, before I send this page for processing on my asp page (which involves saving the data back to the database), I'd like to check whether or not the user has entered the same project/task combination on multiple rows.....the dropdowns on each row are named project1-project40, task1-task40, mon1-mon40 etc.

I'm using VBScript for the server side scripting, but I'll happily incorporate a section of Javascript code if that will offer me a simpler solution.

Any ideas or suggestions are more than welcome here!

The short answer is "do a search for javascript clientside form validation".

you can place a test in the forms onsubmit event handler that makes sure the fields are exactly what you want them to be.

you can even do it with client side vbscript form validation but that would mean your audience would only be internet explorer users.