Could someone Kindly tell me what equipment I would need to do the following:

Network 4 PC's using Internal Ethernet Cards(already have). Share a ADSL connection using an external Ethernet Modem.

Many Thanks

The easiest solution is buying a router. Then set it up like this:

adsl modem==>router===>pc 1
====>pc2
====>pc3
====>pc4

Enable DHCP on the router and set the 4 network cards to receive an IP address automatically, and everything works!

Yeah... get a lynksys router, they r really good even though there r really good routers out there. And assign those machine static IPs cause it's easier to track which IP is what machine. Keep a good track of open and closed ports on the router, and I would install a good firewall on each machine.