@Newbie_Richard 

Hi, thanks for posting question here.

You may refer to this article to know more. And both crossover cable and standard Ethernet cable should be ok.

If two PCs connected to the same router, wireless or via Ethernet cable, the file backup within the LAN will work between them.

To achieve file backup within the LAN using a switch without a router, both PCs need to be configured with static IP addresses.

  @Newbie_Richard 

Here's a step by step guide on how to connect two computers with an ethernet cable - <https>://www.geeksforgeeks.org/how-to-connect-two-computers-with-an-ethernet-cable/

Every one of the three methods would work for you, but the first one is the simplest and cheapest.

In the past a two similar network devices (like two PC's) had to be connected via straight ethernet cable.

Nowadays, the ethernet card ports have auto-sense feature and they can work either with straight or crossover ethernet cables.