My dads harddrive in his old pc is failing, making the screeches of death, and i need to replace the harddrive. Is it possible to get like a 500gig blue drive insert is as a secondary drive backup everything from the failing drive onto that one, then remove the failing drive and boot from that one? I dont have the windows XP installation disks and i dont think he will be able to figure out how to use 7 or 8. So will this work? Or do I need a fresh install on his computer?
Yes, you could do that.
It should work. At most you may have to do a start up repair of windows to let it reconfigure its bootloader settings again.