I apologise for not updating this sooner but you are correct. As I had installed 7 with a 3rd party audio card it had automatically disabled onboard sound in the bios. As soon as I enabled this all was working great. :)
After I failed to find a sound driver for my sound blaster sound card (sb0680, too old apparently), I removed it and installed the driver from the link below to get my onboard working instead. After I installed and restarted, windows 7 still doesn't recognise any audio device connected. Any...