Mutlitrack Recording Software Options

[Okie]

Hiya!!

Okay, first this,... I am a complete dummy in world of digital music recording. I have bought a new Imac and I want to make simple songs. I am looking for cheap (or free) multitrack recording software. Can anyone advice me ??
I just want to make simple songs with my guitar and my lovely voice
But I would like to record it not at the same time and not on the same track. Which program will be the best for me. I heard of Logic etc. but I think it is a little bit to expensive for my first experiments as singer/songwriter.
Well hope to hear soon!!

Oskar

ps. are there illegal copies going round of Logic or Cubase? Or is that not done in this scene??