One of the known issues for Android-x86 4.0-RC2 is no Ethernet supports. So you will not get Internet connection on some devices and VirtualBox using the official Android-x86 builds. However, you may use a custom Android-x86 4.0-RC2 build by Ron M. This custom build has integrated an Ethernet patch (for Internet connection) and Intel's ARM libraries to run ARM applications. So you don't have to get hands dirty by altering computer code and files.
The installation is same as the official Android-x86 builds and can be referred to my step-by-step installation guides below: