jazzing up an mp3 song

[backupboy]

this might sound sad i know, but ive been challenged to get a hold of the old kids tv theme tune "rainbow" and jazz it up into a sort of house/trance/dance song. ive got the theme tune as an mp3 file. but what i want to do is put this whole song onto one of those music creator programs and build all the samples and stuff around it. ive got one program but you can only create using the samples supplied with it. i need to be able to import this whole 2 minute mp3 into the creator and basically build on it. any ideas