Cabling Conundrums – Megabit VS. Gigabit Ethernet Cables

What’s the difference between Megabit (Cat 3-5) and Gigabit (Cat 5e-7) unsheilded twisted pair ethernet cabling?  It uses the same wires and the same connections, so why is it faster?
It comes down to how tightly the wires are twisted.  The more twists, the less electromagnetic interference.  The less electromagnetic interference, the less packets get damaged.  The less packets get damaged, the less packets have to be resent.  The less packets that have to be resent, the faster the network can run.  One third of all network traffic is the header of the packet, one third is the contents, and one third is the footer.  If the header doesn’t match the footer, the packet is damaged and needs to be resent.  You can see how this would slow down the network (and speed it up without it).