Vmware server is a free application, so you need to use Vmware Workstation or ESX server to create your virtual machines. Once you have them added though, you can just connect to the server running Vmware server from any computer using the server console. You can also download pre-made vmware images for different uses on the Virtual Appliance Marketplace.
And yes, you need to register with Vmware before you use this.
For this to work, you need the Canonical repository enabled. Its deb-lines looks like this:
deb http://archive.canonical.com/ubuntu feisty-commercial main
Just do a search for vmware to install it, but the package is called “vmware-server”.