When you install any version of Windows, it customizes itself to your specific device configuration. If you install it on one configuration, then move it to another, it won't boot.
I am going to put together a new computer using some new hardware and keeping some of the old.
I ordered a new motherboard(ASUS P8Z77-V LK ), cpu(Intel Core i5-3570 Ivy Bridge 3.4GHz), memory, graphics card, and windows 7 (64 bit).
I will be using my current hard drive which has windows xp installed.
My question is this, do I put my new computer together and then install windows 7? Or, do I install windows 7 on my current computer then add the new parts?
I am a noob at this and have been researching how to's on youtube.

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