Virtual PC docs say I have to disable trusted execution or update bios.
I am running a gigabyte ex58 ud4p motherboard.
How can I update the bios, is it risking what I have installed on my system now?
You can download the bios update from their website:
To update your bios download the latest version and execute it (it's an executable).
Quote from that link:
The worst that can happen is that you fry your motherboard, but that doesn't mean you lose your data and what's installed on your system. Replacing the motherboard will give you everything back.