Use Acronis TrueImage with a hard drive in an external USB enclosure. You can make a full image of the drive. I find that Acronis works better than Norton. You can buy and download TrueImage for $50 at http://www.acronis.com .
I'm an Acronis convert.
Ghost is like all Symantec/Norton products these days - an absolute resource hog.
They both work well in this context but Acronis for me.
I second this. Acronis Trueimage has worked better than anything else I have tried, particularly for making bootable exact copies of disk drives. You need to bear in mind that not all computers will boot from a USB drive unless your Bios has a setting for a usb drive boot.
Also, only the first partition or drive on a USB drive can be used as a boot file. However, Acronis can also make a bootable CD that will install a workable copy of TrueImage back on to a crashed computer that will then enable you to recopy a "USB drive copy" back on to a non functioning computer.