Here are some websites that you might find useful
  Interactive site with lots of music theory, lovely to use, excellent resource.    

Look for the lovely cartoon version of Peer Gynt. Lots of games too.


    Interactive with music theory, but is a bit wordy. Very useful resource.

Good site for learning the basics of reading music.


Lots of theory, lots of words too!  
You will find a keyboard note finder that will help you locate notes on your keyboard, also many piano chords done in the same way. Very useful tools to have. (Thanks to Vincent McMahon for finding this site)
There are lots of resources on this site for Irish Primary schools. Follow the links to the music pages for lots of music resources.