You need to add more NIC PCI cards onto your desktop. Just make sure each desktop has 3 NIC ports.

Ok I know for a fact that you can re-wire your cat 5e cable into a Cat 5e crossover cable however, this will only allow two of the computers to be networked together. In order to put three of the computers together you would a total of 4 network cards each computer has one except one would house two of them for connection to eachother.

Seriously, get a cheap router. That’s the only way to do it without pulling out your hair trying to configure some computer to act as a switch…

If you do not need internet access from all 3 computers, then a cheap network switch may suffice. You will have to manually configure all the network configurations on the 3 computers. Again, even if just using the “switch side” of a cheap router, it’s a lot easier since the router provides DHCP.

Not easily. With new routers less than $30 and used ones less than $10, why try to build something that probably won’t work?

only if one of them has two NICs and you configure that one as a router… not trivial. workgroup switches are cheap these days, I’d suggest you pick one up…