Ajax no working

Ajax no working

I am using boxy for this pop up register form, however the ajax no working, it does not post to "user.php" nothing happens except an long array append to my index.php like "index.php?username=&userpass=&cpass=&useremail=&name=&phone=&address=&postal=&do=ajaxRegister&submit=Register+Now"

my code
   $('#register').click(function(){
      var boxy_content;
      boxy_content += "<form id=\"registerform\" class=\"formular\"><fieldset>";
      boxy_content += "<label><span>Username: </span><input id=\"name\" name=\"username\" type=\"text\" class=\"validate[required,custom[noSpecialCaracters],length[0,20],ajax[ajaxUser]]\" size=\"20\" /></label>";
      boxy_content += "<label><span>Password: </span>   <input id=\"pass\" name=\"userpass\" type=\"password\"  class=\"validate[required,length[6,11]] text-input\" size=\"20\" /></label>";
      boxy_content += "<label><span>Confirm Password: </span><input id=\"cpass\" name=\"cpass\" type=\"password\"  class=\"validate[required,confirm[password]] text-input\" size=\"20\" /></label>";
      boxy_content += "<label><span>Email:</span><input id=\"email\" name=\"useremail\" type=\"text\" class=\"validate[required,custom[email]] text-input\" size=\"20\" /></label>";
      boxy_content += "<label><span>Name: </span><input id=\"name\" name=\"name\" type=\"text\" size=\"20\"  class=\"validate[optional,custom[onlyLetter],length[0,100]] text-input\"/></label>";
      boxy_content += "<label><span>Phone: </span><input id=\"phone\" name=\"phone\" type=\"text\" size=\"20\"  class=\"validate[required,custom[telephone]] text-input\" /></label>";
      boxy_content += "<label><span>Address : </span><input id=\"subject\" name=\"address\" type=\"text\" class=\"validate[required]] text-input\" size=\"20\" /></label>";
      boxy_content += "<label><span>Postal Code : </span><input id=\"subject\" name=\"postal\" type=\"text\" class=\"validate[required]] text-input\" size=\"20\" /></label>";
      boxy_content += "<input type=\"hidden\" name=\"do\" value=\"ajaxRegister\" /><input type=\"submit\" name=\"submit\" class=\"buttonSubmit\" value=\"Register Now\" /></fieldset>";
      boxy_content += "</form>";
      registerBoxy = new Boxy(boxy_content, {
          title: "Register As A Member",
          draggable: false,
          modal: true,
          behaviours: function(c) {
            c.find('#registerform').submit(function() {
               Boxy.get(this).setContent("<div style=\"width: 300px; height: 300px\">Sending...</div>");
               // submit form by ajax using post and send 3 values: subject, your_email, comment
               $.post("user.php", $('#registerform').serialize(),
                    function(data){
                        /*set boxy content to data from ajax call back*/
                        registerBoxy.setContent("<div style=\"width: 300px; height: 300px\">"+data+"</div>");
                    });

               return false;
            });
          }
      });
      return false;
   });


another problem i want to ask is how to validate the form browser side under this circumference, i implemented one validation plugin but no working in boxy.