I've a different point of view my friend.
4 years ago, I was the first who said: VMWare is the best of the best.. but one of my college finally convince me why examples that Virtualbox is much more better.
Of course, the main point of Virtualbox is his price.. yes, yes, 0$ is brilliant and if you look to their portal, you will realized that the software is well update.
Let's talk about performance. Compared with VMWare, VirtualBox uses less memory and resource.
If you run a virtual machine without installing the Guest Additions driver, you will not face issue like you can have with VMWare. i.e: graphic latency
You have "VBoxManage" (the command-line interface for VirtualBox) that give you a lot of useful tools to manage your "Box" and also "VBoxWebSrv" to run and administrate your virtualization via PHP interface.
But this only my humble opinion and my experience exchanged.
darksabersan.