Networking has gotten a lot easier in GNU/Linux in recent years. Two experiences made me really appreciate this:

1) My laptop has built-in wifi, but I was testing a USB wifi adapter. When I plugged in the latter, Ubuntu's NetworkManager applet allowed me to connect each adapter to a different network. The GUI is smart enough to handle more than one wifi adapter!

2) My laptop connects to the Internet via wifi. I connected a BeagleBone embedded computer via ethernet, and wanted to set up my laptop as a gateway, so that the BeagleBone could connect to the Internet via my laptop. I was prepared to have to set up dhcpd and dnsmasq and so on. But all I had to do was tell NetworkManager that I wanted to share my connection, and it set up everything for me!