Computer naming mainly relates to Windows file sharing, when sharing your files in a workgroup or domain all the computers must have unique names.

The names are there for your convenience, so you can recognize which computer you want to connect with to grab a file or print a document.

The names are visible to others on the same network, so if you name your computer "Spanky's Laptop" and go to a Starbucks you may get an odd look from a few geeks looking at which computers are on the network.