Getting jquery to work with custom theme

I am trying to get some jQuery plugins to work with my custom theme.

Up until now I was doing this:

function my_scripts_method() {
  wp_deregister_script( 'jquery' );
  wp_register_script( 'jquery',    'http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js');
  wp_enqueue_script( 'jquery' );
}    

if (!is_admin()) add_action('wp_enqueue_scripts', 'my_scripts_method');

But I’ve read one shouldn’t deregister core bundled scripts and replace them with other versions. So I’ve dropped that from my functions file.

The issue is now that I’ve dropped that, none of my jquery scripts work. For example, my image slider. I am calling their scripts like so:

// Enqueue Nivo Slider
function maglite_add_nivo() {
    wp_enqueue_script( 'nivoslider', get_template_directory_uri() . '/js/jquery.nivo.slider.pack.js', array( 'jquery' ), false, true );
}
add_action( 'wp_enqueue_scripts', 'maglite_add_nivo' );

It just doesn’t work now, I am guessing it has something to do with jquery not initializing or something.

I am getting some type errors in my console, which related to the nivo slider I am adding. Specifically this line: $(window).load(function() { the console says:

TypeError: 'undefined' is not a function (evaluating '$(window)')

I feel like I am missing a core step to including custom scripts that require jquery. Should I still enqueue jquery or do I not need to do anything with jquery and enqueueing?