From what controlpanel are you migrating from? Just the one account are are there many accounts? Beyond the website are there other things that need to be migrated? For example MySQL databases, email accounts etc.
Do you still have access to your old controlpanel? (It might be easier during the process than working from a single proprietary backup file)
I migrate from Cpanel to Direct Admin. At this moment i have about 103 account, but many of this account havn't any files. I only transfer backup of these account to new machine. Yes, i have acces to old machine.