It's really simple — Out of the box, Virtualbox has the capability to read VMware .vmdk files, although I did convert mine to native VirtualBox .vdi files with the following command:
VBoxManage clonehdWith VirtualBox, you also don't have to do anything out of the ordinary to setup port forwarding from the host OS to the guest OS. Just remember that the default guest IP address in VirtualBox is 10.0.2.15. So adjust your network settings accordingly.
Also, VirtualBox let's you play around with virtualised deployment tools like Vagrant, which currently does not support VMware.