Comment by Xenograph

It's in the title of the post. You can run your VM in a regular window but at high performance (think gaming and professional stuff that's GPU heavy). You otherwise can't do this without a hardware KVM switch (or tossing the VM and just dual booting). Hardware KVM switches are expensive and often don't work very well. And still, with a KVM switch it wouldn't be running inside a window. It would consume your whole screen.