I have a server running the free version of ESXi. This server hosts four guest Virtual Servers, all Windows. I need to make sure these machines are all backed up, and currently use Acronis Backup & Recovery 10 to do so. Acronis DOES offer an ESXi agent, but it will not work with the free ESXi. I would like to be able to backup the entire datastore on the ESXi server to make disaster recovery as simple as possible in the event of hardware failure. What is the best VMWare product to upgrade to from the free version of ESXi that will allow me to do this, and is it a simple upgrade or a rebuild of the entire server??? Thanks.