Computers on a network need unique names so they can identify and communicate with each other. It's best to keep computer names short (fifteen characters or less) and easily recognizable.
We recommend that you use only Internet-standard characters in the computer name. The standard characters are the numbers 0 through 9, uppercase and lowercase letters from A through Z, and the hyphen (-) character. Computer names cannot consist entirely of numbers, nor can they contain spaces. The name also cannot contain special characters, such as the following:
< > ; : " * + = \ | ? ,
Some Internet service providers (ISPs) require you to use a specific computer name so they can identify your computer and validate your account. If your ISP requires a specific computer name, don't change the name they give you.
Open System by clicking the Start button , clicking Control Panel, clicking System and Maintenance, and then clicking System.
Under Computer name, domain, and workgroup settings, click Change settings.
If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
On the Computer Name tab, click Change.
Under Computer name, delete the old computer name, type a new computer name, and then click OK. If your computer is part of a domain, you will be prompted to provide the name and password of an account with permission to rename the computer in the domain.