My PC has two network cards but I only have one port on the LAN to plug it into. Recently I acquired a laptop that I'd like to share the port with.
Can I just somehow configure the PC as a switch and plug the laptop into the other port to do this?
One way is to "Bridge Connections", this way your PC acts more like a switch than with Internet Connection Sharing, which makes it act like a NAT router.
Yes you can. Its called Internet Connection Sharing. Just follow the directions, its fairly easy to set up.
If this daunts you, you can just buy a switch to do the sharing.