You have a few options, if you open the converter tool, the first step decides what the source is. You can do either that machine, one from a server, or another VM. Next you just type in the IP of your ESX server w/ proper authentication and finish the next few steps for where to store the vmdk file. (I recommend using a GB network) Once completed it should show up (off) and then you should have to just turn off the physical and turn on the VM. This has worked flawlessly for at least 4 physical server moves thus far.