Using JQuery to find the next table row

<tr>
 <td class="expand"><img src="plus.gif"/></td>
 <td>Data1</td><td>Data2</td><td>Data3</td>
</tr>
<tr class="show hide">
 <td> </td>
 <td>Data4</td><td>Data5</td><td>Data6</td>
</tr>

$(document).ready(function(){
	$('.expand').click(function() {
		if( $(this).hasClass('hidden') )
			$('img', this).attr("src", "plus.jpg");
		else
			$('img', this).attr("src", "minus.jpg");

		$(this).toggleClass('hidden');
		$(this).parent().next().toggle();
	});
});

$(document).ready( function () {
    $(".expand").click(function() {
            $("img",this).attr("src",
                 $("img",this)
                    .attr("src")=="minus.gif" ? "plus.gif" : "minus.gif"
            );
            $(this).parent().next().toggle();
    });
});

//this will bind the click event
//put this in a $(document).ready or something
$(".expand").click(expand_ClickEvent);

//this is your event handler
function expand_ClickEvent(){
   //get the TR that you want to show/hide
   var TR = $('.expand').parent().next();

   //check its class
   if (TR.hasClass('hide')){
      TR.removeClass('hide'); //remove the hide class
      TR.addClass('show');    //change it to the show class
      TR.show();              //show the TR (you can use any jquery animation)

      //change the image URL
      //select the expand class and the img in it, then change its src attribute
      $('.expand img').attr('src', 'minus.gif');
   } else {
      TR.removeClass('show'); //remove the show class
      TR.addClass('hide');    //change it to the hide class
      TR.hide();              //hide the TR (you can use any jquery animation)

      //change the image URL
     //select the expand class and the img in it, then change its src attribute
      $('.expand img').attr('src', 'plus.gif');
   }
}

<tr>

<td colspan="2" align="center"
<input type="image" src="save.gif" id="saveButton" name="saveButton"
    style="visibility: collapse; display: none"
     onclick="ToggleFunction(false)"/>

<input type="image" src="saveDisabled.jpg" id="saveButtonDisabled"
      name="saveButton" style="visibility: collapse; display: inline"
      onclick="ToggleFunction(true)"/>
</td>
</tr>

ToggleFunction(seeSaveButton){
    if(seeSaveButton){
        $("#saveButton").attr("disabled", true)
                        .attr("style", "visibility: collapse; display: none;");
        $("#saveButtonDisabled").attr("disabled", true)
                                .attr("style", "display: inline;");
    }
    else {
        $("#saveButton").attr("disabled", false)
                        .attr("style", "display: inline;");
        $("#saveButtonDisabled")
                        .attr("disabled", true)
                        .attr("style", "visibility: collapse; display: none;");
    }
}