Booting old hard drive on new computer to recover data?

Basically my computer died (prob CPU/Motherboard) and my parents are getting me a new computer. Unfortunately, my Ext HD arrived one day to late from me to back up my stuff. My question is would I be able to boot from my old HD on my new (dell xps 7100 probably) and put all my stuff onto my external hd. (I do not... show more Basically my computer died (prob CPU/Motherboard) and my parents are getting me a new computer. Unfortunately, my Ext HD arrived one day to late from me to back up my stuff. My question is would I be able to boot from my old HD on my new (dell xps 7100 probably) and put all my stuff onto my external hd. (I do not intend to continually use my old HD). I probably cannot use Repair install as it was my cousin who installed windows and I don't have the CD and we have had a falling out.
Update: I password protected my main account on the old xp install, would that affect me from recovering my data indirectly (via using my old hd as a 2nd hd)
Update 2: I'm asking if its possible to boot from the old HD with the new PC, that means using the old OS etc. If not, thats when I want other advice.
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