How do you connect a laptop and a PC together?

One way is "adhoc".
If you have High speed internet, then maybe use a router, maybe wireless. If you get a Wireless router, disable wireless when not using. You could access the Internet with both Computers at the same time.

More info

What operating systems on each?

Do you have a switch or router or would you want a direct cable to connect to each or wireless

Do each have an ethernet card

Are they next to each other or separate rooms

The more info provided would help to help out