iTunes closes when I close my powerbook

[Chu]

Ok so here's the situation, I want to be able to close my powerbook and leave iTunes playing, either throught the built in speakers or out the headphone output. This is so I can have tunes playing through my system without my cat walking all over my mac.

Am I being incredibly dim?

Any help much appreciated,

Cheers,

Chu

P.S sorry if this posts in the wrong place.

EDIT: I don't mean iTunes actually closes just that the audio stops.
EDIT2:And by close I mean shut the lid not shut down, that would be dim.

[Big Jim]

I suspect that closing the case is putting the Pbook to sleep, which would cut audio and wireless off. Can you not site the Pbook somewhere that the cat is not allowed or unlikely to go?