asp.net mvc 3 - ajax form submit and validation

I am sorry if this has been asked already, but I have been looking for sometime but all I have found are rather old posts (mvc1, mvc2). I have a form which I would like to submit via Ajax.

This looks like it would work but does not cover server side validation.

1) I am unsure if I should use the AjaxHelper.BeginForm or use raw jquery calls ($.ajax)? What is the recommended approach here?

2) How do I handle client and server side validation? I am hoping the mvc framework provides a built in mechanism for dealing with this? There are some validations which I am only doing server side. Would using a ValidationSummary still work here?

I am using asp.net mvc3/razor with unobtrussive javascript validation.

Thank you!

Edit: (as requested by Bobby B below). This was added months after asking the question as a user wanted to know how to use AjaxHelper

This is the javascript code I used:

<script type="text/javascript">

function ajaxValidate() {
  return $('form').validate().form();
}

function getGbPostSuccess(ajaxContext){
  // .... it is not necessary to do anything here.
}
function showFaliure(ajaxContext){
   // handle failure
}

HTML snippet:

@using (Ajax.BeginForm("Index", "Home", new AjaxOptions
                        {
                            UpdateTargetId = "form1",
                            InsertionMode = InsertionMode.Replace,
                            OnBegin = "ajaxValidate",
                            OnSuccess = "getGbPostSuccess",
                            OnFailure = "showFaliure"
                        }))
{