Migrating a physical 64bit Linux to become a guest OS on VM


Hi all!

In a little while I will be transferring a physical 64bit Linux machine to become a guest OS on a (yet to be installed/configured) virtual machine host.
I’m still hesitating a bit between KVM, VirtualBox & VMware for this host.

If I choose for VirtualBox, how easy will it be to migrate the HD with the partitions of the physical server to become a guest OS on the virtual machine host?
Is it as simple as creating images & config for the guest machine, mounting both these and the physical disk containing the originals, and doing a ‘cp -a’?
Will this work with VirtualBox?

Any thoughts, info & help is greatly appreciated!