How to keep win 7 with new hardware

I am going for the 2 year upgrade from my current gaming system (still pretty good), effectively a new build- wont list components unless someone really wants them, as its not particularly relevent. I want to keep my existing hard drive system and transfer them all across to the new rig, as the thought of d/loading 5Tb of legal software and games again is just tooo much to contemplate.

I am aware that a straight swap over does not work, and I recall that drivers need to be removed (could well be wrong here)- does anyone know what needs to be prior to transferring to the new rig to maintain win 7? Thanks :)