I have gotten the Fez Cobra to work under Windows XP and Visual Studio 2010.
I am posting this information in hopes that this will help someone with similar problems.
]Host system is a Mac-Mini 2008 (MAC OS X version 10.6.8, Processor 2 GHz Intel Core 2 Duo, Memory 2 GB 667 DDR2 SDRAM)/:m]
]Virtualbox Installed on Mac-Mini (Version 4.2.14 r866644)/:m]
]Windows XP pro installed with service pack 3 (All .NET updates from 2.0 to 4.0 and service packs installed)/:m]
]Visual C# 2012 installed/:m]
]GHI SDK for 4.1 installed/:m]
]Manual installation of GHI_NETMF_Interface driver installed to USB controller./:m]
]Please note Windows ID’s the Fez Cobra as EMX but then cannot find the driver!/:m]
]Virtual extension pack installed also to support USB 2.0 EHCI controller./:m]