Actually, I found JavaScript harder than PHP. PHP is much more strict and clear than JavaScript. but, there is some Sitepoint.com books and tutorials that are good.
Seb: Don't be an ass. Of course there is Google, but he is asking for suggestions on sites that people found particularly useful. I'd recommend http://www.w3schools.com/ for sure. They have quite a few good beginning tutorials on Javascript.
I keep tizag and w3schools bookmarked. They're not perfect, but they're great for simple syntax questions and the like. I'm with allaire, I found JavaScript to be tougher than PHP, especially when you start considering cross-browser problems.