So I'm new to building/upgrading computers and I just got a Asus p4-p5g41 to kind of tinker around with and put some of my old software on and I'm trying to do some upgrades on it but I have some questions. First is it possible to put two hard drives in this computer especially with it's smaller forum factor? I was planning on getting the adapter to put one of the old laptop hard drives I have in it and was thinking about then putting a small ssd in it as well but I'm also wondering if putting an ssd in there will give it any performance improvement since it is a 10 year old computer? The other thing I'm trying to figure out is the guy I got the computer on said if I put one of my old hard drives in it that the computer would accept the operating system and I would not have to purchase one or a license but I always thought that the windows 10 was tied to a serial number or something of the original computer that the operating system was shipped with so what is actually the deal with that? Thank you in advance for your help.