Thanks guys, I bought the cheapest HD series card (HD5450) for ~30 euros and fixed the bug.

Does that mean the first real usage of 'Oxygene for .NET' as a development tool for game development? That's pretty exciting actually. If you want help with such a task, you should contact RemObjects and tell them what you intend. I'm sure they will be more than helpful knowing what a milestone this would be for them.
If we talking about XBOX, much still depends on my publisher.
My current project is very large (first and third person steering, 11 types of vehicles, newton physics) and it would be better to use Oxygene for something smaller... in the beginning.