Using an external USB hard drive to boot

Does anyone know if you can boot from an external USB hard drive such as a Passport?  The hard drive on my Inspiron 5160 is getting iffy and we've had to rebuild the system three times since January.  I finally determined that the hard drive was the problem and ran a full disk check on it (took a day or too) and for now, everything seems to be okay but I can see the handwriting on the wall.  Since internal hard drives seems to be hard to come by (except for rebuilt ones) and space is at a premium in my house, I hope this might be an option.

Thanks.