I've always had Windows as the host (Primary) OS and Linux as guest, using VirtualBox. 1  Linux in a window - simplest approach: You get a window that is a new computer with linux. It's got network access over NAT, and each machine can't really see each other. Seamless Mode: a VBox feature that boils down to have the linux's background transparent, so you can see (and click) the Windows behind it.