Solved Copy XP from old HDD for XP/8 dual boot

Hi Apologies if this has been covered before, I have retrieved the HDD from my old laptop which used XP, it's now sitting in a caddy hooked up to my current W8 machine and I'd like to be able to boot up using 8 or XP. I've created some space on the internal HDD in which to put the content copied from the old HDD as I understand booting from an external drive can be trixy. I'd be grateful if...