<table style="border-collapse: collapse;" align="" width=""><tbody><tr><td><div class="loginform">
   <form name="loginForm" method="post" onsubmit="javascript:showBusyLayer()" action="">
   <div class="formlgn">
<label><span>Логин:</span><input class="loginField" type="text" name="user"></label>
<label><span>Пароль:</span><input class="loginField" type="password" name="password"></label>
   </div>
   
   <input name='sbm' value="" type='image' src='javascript:document.loginForm.submit();' class="btn">
     
     
     
   <div class="clr"></div>
   <p><a href="$REMINDER_LINK$">Забыл пароль</a> | <a href="$REGISTER_LINK$">Регистрация</a></p>
   </form>
   </div><br></td></tr></tbody></table>

.btn:hover {
  background: transparent url(http://mixgame.azuli.org/templates/xfun/images/login_btn.png) left bottom no-repeat;
}
  .btn {
  float: left;
  width: 42px; height: 42px;
  background: transparent url(http://mixgame.azuli.org/templates/xfun/images/login_btn.png) left top no-repeat;
  outline: none;
}

<table style="border-collapse: collapse;" align="" width=""><tbody><tr><td><div class="loginform">
  <form name="loginForm" method="post" onsubmit="javascript:showBusyLayer()" action="">
  <div class="formlgn">
<label><span>Логин:</span><input class="loginField" type="text" name="user"></label>
<label><span>Пароль:</span><input class="loginField" type="password" name="password"></label>
  </div>
   
  <input class="btn" src="javascript:document.loginForm.submit();" name="sbm" type="submit" value=""/>
   
   
   
  <div class="clr"></div>
  <p><a href="$REMINDER_LINK$">Забыл пароль</a> | <a href="$REGISTER_LINK$">Регистрация</a></p>
  </form>
  </div><br></td></tr></tbody></table>

<style>
  .btn {
  float: left;
  width: 42px; height: 42px;
  background: transparent url(http://mixgame.azuli.org/templates/xfun/images/login_btn.png) left top no-repeat;
  outline: none;
  border: none;
}

  .btn:hover {
  border: none;
  background: transparent url(http://mixgame.azuli.org/templates/xfun/images/login_btn.png) left bottom no-repeat;
}

  </style>