Running escribe on a mac sucks, unless you want to spend money on parallels or such, but for those running virtualbox I'll give a couple pointers:
1) If your Windows install needs drivers before it can reach the Internet, you can download them to your flash drive - just remember that you need to virtually eject the drive on the Mac before you can access it in the virtualbox Windows environment.
2) To access the DNA200 on Windows, you need to set up a USB filter for it in Virtual Box. In the virtualbox Manager, go to Settings->Ports->USB and you should be able to add it there. If it's not showing up, disconnect and reconnect the DNA200 device. If that doesn't work, check that it is showing up on your Mac's USB hardware by going to About This Mac->System Report->USB. If it's not showing up in USB device tree list, then your problem isn't with VirtualBox.