Definately purchase a DSL/Cable router, I have had good luck with the Linksys model BEFSR41 and it's under $100. It has four ports so both PCs can hook right into the router without the need for a seperate hub. The router works as a DHCP server so you don't need to come up with your own IP addresses, the setup info shows you what to do.
The NICs can be any brand it, they don't have to be the same. Just make sure that they can work with 100BT. I personally like Intel Pro 100 NICs, just make sure that they are PCI and not CNR slot cards (CNR is a newer slot for NICs).
And don't forget to pick up three CAT5e cables too!