You will not be able to carry over a power supply and RAM from eMachines. The problem with pre built systems is that for the most part they use a lot of proprietary form factors that make upgrading difficult or near impossible. That RAM will be way too old to work on modern Z77 systems.
The reason being is that the RAM will be too slow and the voltages won't match. Modern RAM isn't that expensive though. The PSU most likely won't fit into that Phantom 410, nor will it have the proper power and voltage connectors, so you will have to purchase a new one.
That Windows license is married to the motherboard - you will not be able to use it on a new machine legally. You can reuse the disc but you will most likely have to purchase a new activation code.
As far as the HDD transfer that's easy - just do a quick format in Windows install when Windows prompts you for it. That's the least difficult part of that process.