My issue is nearly identical to this question. I tried those solution and none worked. But I am using a different Android x86 image. I\'m using the ICS (4.0-RC1) asus_laptop ima
Some sources in the net says you should use the PCnet-Fast III either in bridged mode or NAT in your VBox Machine settings. Just give it a try.
This is a guide i found, but to be sincere, i am new to Android on VBox (and to Android at all) and i didn't test it myself.