Good article about dual- booting using software.  However, dual-booting using hardware is way more versatile and much less hassle once you get set up.  Assuming you have a desktop PC and one SATA drive, buy another Sata drive.  Then build a SATA switch.  Go to http://www.thesataswitch.com/ for directions on how to build one.  Then you can do whatever you want to either drive, completely independent of each other.  If you add a third drive you can triple-boot any three different OS's!