Need some help combining 2 jQuery scripts and behaviors
===

Ι need to use a combination of the following 2 scripts but despite all the combinations I've done so far, I fail to get it to work 100%.

I use a colorbox to display products detail pages in which there is a form with various fields for adding the items to the cart. Upon submitting the form, I want to show an alert and then close the colorbox so that the underlying page (that opened the colorbox in the forst place) stays as is.

With this script 

    $("#productadd").submit(function(){ // WORKS FINE EXCEPT THE ENCODING
      $.post(
        $(this).attr('action'),
        $(this).serialize(),
        function(data){
          alert('Product was added to your order');  
        $().colorbox.close();
    });

everything works fine except for the encoding which in my case is iso-8859-7 (greek).
If I use this script then encoding is ok but the post is being made with the default behaviour, redirection to the url defined in the form's action.

		  $("#productadd").submit(function(){ //ENCODING OK, COLORBOX.CLOSE() AND ALERT FAIL
			 $.ajax({
				data: data,
				type: "POST",
				url: $(this).attr('action'),
				dataType: 'json',
				beforeSend : function(xhr) {
					xhr.setRequestHeader('Accept', "text/html; charset=iso-8859-7");
				},
				success: function(json) {
					alert('Product added to cart!'),  
					$().colorbox.close(),
					itemAddCallback(json);
				},
				error: function (xhr, textStatus, errorThrown) {
					$("#error").html(xhr.responseText);
				}
			});

I've tried using the following but with no luck:

    $("#productadd").submit(function(event){
      event.preventDefault(); // prevent submission of the form and send ajax
      $.ajax({
        data: data,
        type: "POST",......




If there's a jQuery equivalent for xhr.setRequestHeader('Accept', "text/html; charset=iso-8859-7") I'd be more than happy to use it. **Also, what do I declare as data: so I dont get a 'data is not defined' error?** (despite the error, date submits fine).