I'm surpised with the comments here about learning Javascript. Let's not forget - you don't want to learn it all! While the language is quite great if used correctly, it has a tainted history and many horrid parts. Luckily, you really only have to listen to a single voice:
Douglas Crockford also wrote The Good Parts, which is a nice little Javascript book. He does a bunch of stuff at Yahoo! and has materials on their YUI Theater that explain the problem quite well:
http://developer.yahoo.com/yui/theater/
