Vista Home premium install

Hi,

I'm upgrading a Windows media centre edition computer with the following
specs:

Processor: 2.8Ghz
HDD: 300GB
Memory: 1GB
Graphics: Nvidia 7500LE

I'm trying to upgrade to home premium edition but it says can't upgrade
during the process and instead it will install Vista and move all the XP
files to another folder(fine).

It nearly completes the installation but at the end freezes and rolls
back to Windows XP.

The upgrade advisor is mentioning that the realtek high definition audio
device is incompatible with Vista. Does this have something to do
with the install failure as I thought it would just install Vista anyway?

Any insight would be appreciated.

Thanks,

Andrew

p.s I've uninstalled Norton AV 2006