partner-contact/partner_firstname/res_user_view.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
  <data>

    <!-- Replace name with first name and last name -->
    <record id="view_users_form" model="ir.ui.view">
      <field name="name">res.users.form.firstname</field>
      <field name="model">res.users</field>
      <field name="inherit_id" ref="base.view_users_form"/>
      <field name="arch" type="xml">

        <label for="name" position="replace">
          <label for="firstname" class="oe_edit_only"/>
        </label>

        <field name="name" position="replace">
          <field name="firstname"/>
        </field>

        <label for="login" position="before">
          <label for="lastname" class="oe_edit_only"/>
          <h1><field name="lastname"/></h1>
        </label>

      </field>
    </record>

  </data>
</openerp>