I have an GT220 in my system. Is it connected via HDMI cable? I had alot of trial and error getting mine to show the initial AV-Wizard, but in the end what helped was,
Boot core/hybrid when you see the "Kubuntu" splash screen press the "shift" key repeatedly. You'll hear several beeps. Once the screen goes blank, i pressed "1" waited, no change. Pressed "2", waited no change. Pressed "3" waited.... viola AV-Wizzard.
I only need to get the HDMI audio to work now.
This was my experience to get it working, it might or might not work for you. Try numbers from 1-6 and see what happens.
Thats my 2cents worth.