Finding missing drivers

I want to create a hard drive image of the C: drive on my new laptop computer which has Windows 7 before installing any software on it, including Norton Ghost. So I plan to run Norton Ghost 15 from the Symantec Recovery CD rather than installing the software first on the hard drive (I don't want Ghost to be in the backed up image). I am trying to back up the system drive image onto an external USB hard drive. Although I connected the hard drive to a USB port before booting the PC from the Symantec CD, the external USB drive does not appear in the list of drives that I can back up to when Ghost runs from the CD. How can I locate the USB driver on my Windows 7 hard drive so that I can install it manually when I run Ghost from the Symantec CD? I will also need this driver to restore the system drive disk image later, which also requires me to run Ghost from the CD.  Thanks!