LSDJ is good, if you want something like 8-bit music. (think Sabrepulse, or Unicorn Kid.)
Garageband really :/ thats the best i know
I like to use spiralfrog or yahoo music. with spiralfrog you can only have the music for about 3 months to 5 then you have to download the music again BUT this way is legal and free. yahoo you have...
Jazz was very popular because the 1920's were referred to as the "Jazz Age"
Audacity is a good free audio recording program. There aren't any free programs with all the features of Pro Tools, Cubase, Logic, Sonar or Fl Studio.