var $j =
jQuery.noConflict(); is a valid statement since the jQuery.noConflict() will return a reference to the jQuery(). So you can use your $j() instead of $().
slick101, if you're getting "Error: $ is not a function" error, that's probably because you are using $ somewhere instead of $j
OR
you included your mootools plugin/script before you included mootools.js javascript file.