hdmi sound problem

Hi. I am posting this again as my original post only had the title and the full explanation of my problem and things I have tried disappeared. Also, if you read below, I think I have found something out really important. I added onto the end of my original post but got no replies. So I am hoping posting as a new topic, someone will maybe be able to confirm my findings and has an existing warranty and can contact dell support.

I have read different things on many forums. Dell say that audio is not carried - well I know this is not true as I can switch the audio manually from laptop to hdmi. I have tried all the fixes in this forum and others, such as re-installing sound card, chipset, even graphics card some people suggest has something to do with. Some say it is not possible and you just have to do it manually.
 My friend has a HP laptop and it switches sound straight away as soon as the HDMI cable is plugged in. So I know that Windows or at least HP can do it.
 At the weekend, I installed Ubuntu. I have never used it before. I wanted to see what all the fuss is about. I have a dual boot now and maybe longterm may ditch windows. Anyway, I logged into Ubuntu, loaded a video and plugged my HDMI cable and the audio and video came through my tv straight away.
 So, this to me says it is a windows thing or maybe dell drivers.
 My warrantry has expired and dell are not willing to help. I am hoping someone at dell will read these findings and do something about it. Or maybe someone else who is experiencing the same problem who has a current warranty can explain to Dell that this works in Ubuntu.