HDMI with a Viring+ Box

Hi everyone, Me and My Step-mum have been wondering about getting our HDReady TV in HD mode using the Virgin+ Cable Box. Our TV is fairly old and so it only has a DVI connector whereas the virgin box only has a HDMI port, We've got it connected via a HDMI-DVI cable and I managed to find the setting searlier today, however, Whilst fiddling with it I managed to get the HD working but without any sound, I know this is because HDMI cable transmits sound and visuals whereas DVI only transmits Visuals, is there any way that we can get the Audio to work in HD mode without having to buy a new TV. Any input would be appretiated.

Thankyou.

EDIT: I realise I've spelt Virgin wrong in the title, using a horrible horrible keyboard to type on.