In my experience you can't, with a new PC your better off with a clean install, no old drivers and registry errors to clog things up. I only use a clone in a HDD replacement scenario when your using the same PC. The version of Windows 7 on a pre-manufactured PC is OEM, which is non transferable, it can only be used on that PC. I usually Install fresh, if you don't have a windows install disk ask a friend, enter no key at install and then use this
place for keys, they're cheap, and use the Key Update Tool afterwords and it will be genuine.
Just my 2 cents do with it what you will.