Set the second drive as a Master and disconnect the Vista drive temporarily , load XP on to the second drive , get everything you need on to it then reconnect the Vista drive . Reboot the PC and enter the bios , under Advanced ( although I am working from an Award bios here ) look at the top entry for choosing which hard drive you wish to boot from ( highlight and press page up or down to select ) press esc. twice then f10 and enter . This is NOT the section where you can choose to boot from CD or Floppy ect. , this is the section above that . You will now be able to choose which OS to boot into and will be able to see each hard drives files from the other in Windows Explorer .