If you're not much for office computers, and like using your own powerful PC at your workstation, then chances are, you're going to have to login to the network. Microsoft shows you how to quickly login and join a Domain or Workgroup in an office network.
A domain is a type of computer network commonly found in the workplace. (In technical-speak, it's a collection of computers that's centrally administered and operates under common rules.)
The Windows 7 Professional, Ultimate, and Enterprise editions are designed to join a domain quickly and more securely. Just follow the easy-to-use wizard, which prompts you to enter your network credentials. A few moments later you're in business.