I have noticed that KVM kernel modules are loaded by default. I have also noticed that there is a VirtualBox package offered for installation. Haven't tried myself, but found several warnings about VirtualBox not working well with KVM modules loaded. I have not tried VirualBox yet, but KVM seems to be working find with images I used on my old Vector Linux installation.
I wonder what happens when one installs VirtualBox. Are KVM modules still loaded by default, or they are replaced by corresponding vbox kernel modules ? KVM better suits my needs at the moment, but there are many ready made VirtualBox images out there offered for download. I suppose some people would want both, not in the same time. I have no problem with removing and loading kernel modules from command line. However, some people might run into problem not knowing that KVM modules are loaded by default. Perhaps there should be some kind of warning somewhere.