Well when i connect all the cables up the gp2x still plays the sound as well as the tv.
any help?

sorry if this has been previously posted but i searched b4 i posted this and couldnt find any help

This happens to all GP2Xs. You'll just have to plug in headphones to get rid of speaker noise.

Although this results in sound playing through headphones and not through the TV.

Sucks.

You could use a headphone-to-RCA lead like those supplied with minidisks to get around the problem, I reckon. There's usually an RCA + Svideo input to TVs - just input audio from the headphone socket.

Works on my mum's laptop

Try this:
Speaker Toggle

Works fine for me.