Those are very doable with the Duemilanove (except for maybe the last one 
). You gotta learn to start small, be patient and work your way up though! Take a look at these tutorials:
http://tronixstuff.wordpress.com/2010/04/30/getting-started-with-arduino-–-chapter-four/
^The linked one is pretty applicable to you, keep in mind a lot of the things in the videos such as the pulsing lights to the music and RGB LED PWM control are much more complicated then they look 