Hi agamemnon
It looks you want something simple, so I'll try to keep this simple too...
My home setup is very near to what you want to do:
PC1:
AMD K6-3 @ 450 MHz running Windows 98
One LAN card
All drives shared with PC2
Prints to PC2's printer.
PC2:
P3 @ 600 MHz running Windows XP
LAN card 1 connected to cable modem, IP assigned from ISP via DHCP
LAN card 2 connected to PC1's LAN card wia twisted-pair cable.
Printer, ZIP and all drives shared with PC1
1) There's no need for any protocol other than TCP/IP;
2) The twisted-pair cable is enough for two PCs, if you don't care that PC2 needs to be powered on for PC1 to print and have access to broadband internet. If that's your case, there's no need for hubs nor hardware routers/switches.
3) For PC2 to act as internet gateway for PC1 you can use WinXP or Win98SE 's built-in Internet Connection Sharing or some sort of routing NAT software like WinRoute Lite. For file/printer sharing, no additional software is needed.
4) Hardware brands are not important at all.
5) Some cable modems can be connected to the PC via USB... If your cable modem is connected to your PC via USB (mine *is not*), you don't need an additional LAN card.
This setup is what I'm using since five years ago... no problems at all and it even works fine when I play with Linux distros...