qemu wont boot ubuntu

[Paul S]

What's the trick to boot an ubuntu disk in qemu?

I've tried as follows:

paul :~/Desktop$ sudo qemu -boot d -m 492 -soundhw es1370 -cdrom 
./gutsy-desktop-i386.iso -hda /media/sda5/virtualhardriveTest.iso

It boots and starts loading, but gets stuck and drops to a busybox with 
the message:
/bin/sh: can't access tty; job control turned off

There are no messages in the terminal.

I've had this on gutsy disks as well as a dell iso.

TIA