VMware Converter 4.0.1 is Free Tool now fully compatible with vSphere 4. One of the great features is Thin Provisionning. What is this? The name is a bit confusing, but in real it's really great, because it saves you tonnes of diskspace. Oh yes!!
When you converting your physical server into virtual, you can chose whether or not to use thin provisioned disks. In my example I was converting a server with 80 Go of physical disk and I chose to use thin provisioned disk in my Virtual Environement, because the VMDK file after conversion is not 80 GO but only something like 8 Go. You see…? Then it will expand (grow) as you install more and more applications inside of your virtual machine server.