VBox only adds layers of "abstraction" to the existing drivers, so I doubt it will solve that problem. Make sure you're using the latest actual nvidia drivers, not the basic ones bundled with windows, and that they're for the right card and the right windows version.

Actually, the problem could be that cgminer is tuned for AMD cards (OpenCL), where CUDAminer is best for nVidia cards (CUDA) such as yours. It's popular for scrypt mining (for litecoins), but can be used for bitcoin too. Here's another discussion on it: https://bitcointalk.org/index.php?topic=173034.0 and another: https://bitcointalk.org/index.php?topic=320079.0

You might do well to just mine some litecoin with it. Bitcoin's hardly worthwhile to GPU mine these days.