Clone ESX Image
If you just want to clone an image on the same ESX box, it should be a simple right-click opeartion. But to clone an image from esxBox1 to esxBox2, it's more work.
In vSphere Client, go to esxBox1 and power-on your image. I've only tried this with WinXP.
In VMware vCenter Converter Standalone Client, click Convert Machine. For this to work, I believe you must select "Powered-on machine" as the "source type". Then you enter your source machine's host, OS username/password and OS Family, and click Next.
Agree to "Automatically uninstall the files when import succeeds." and click Yes to continue. This takes a few minutes.
Select "VMware Infrastructure virtual machine" as the "destination type" and specify the ESX server and the credentials you normally use. That might be tricky. It prefills the ESX server name with a specific machine. What you actually want is the machine name (probably an alias for a group of machines) that you use when logging into vCenter. Likewise, the username/password are the credentials you use to log into vCenter.
Click Next. You may get a warning about the remote hosts certificate. Ignore it. Select the destination ESX box (left-hand-side) that will host your cloned image. It shows you what each of them contain (right-hand-side), which helps you pick the correct box.
Click Next. Choose the disk with the most free space. And agree until it finishes. It takes a few minutes to submit the job, the is shows status and estimated end time. It took me ~3hrs to clone a 20gb WinXP.