When you bought a new computer with the OS already installed, you might want to change the computer name they have used. While I manage a computer shop business, I have dealt a lot of this because transferring workstations from different places requires me to change their names so they will match on the server.
It is simple to change your computer name in Windows 7. The easiest is typing sysdm.cpl in the start menu. You can then change the name easily.
Another method I use is to right clicking my computer, then selecting properties. It will then redirect you to above. You can then change your computer name to your desired name.