Okay - it sounds like your links to jQuery and / or SPServices aren't good. Putting the code into a CEWP shouldn't be a problem though.
Can you try replacing the jQuery link with this please: http://code.jquery.com/jquery-1.8.3.min.js, and see if any alert fires for it?
Can you try replacing the jQuery link with this please: http://code.jquery.com/jquery-1.8.3.min.js, and see if any alert fires for it?