Microsoft Knowledge Base Article 314934 contains the following summary:

This step-by-step article describes how to use Group Policy to automatically distribute programs to client computers or users.

You can use Group Policy to distribute computer programs by using the following methods.

Assigning Software

You can assign a program distribution to users or computers. If you assign the program to a user, it is installed when the user logs on to the computer. When the user first runs the program, the installation is finalized.

If you assign the program to a computer, it is installed when the computer starts and is available to all users that log on to the computer. When a user first runs the program, the installation is finalized.

Publishing Software

You can publish a program distribution to users. When the user logs on to the computer, the published program is displayed in the Add/Remove Programs dialog box, and it can be installed from there.

NOTE : Microsoft Windows 2000 Group Policy automated-program installation requires client computers that are running Windows 2000 or later.