bueno la direccion es esta

http://drupal.org/node/166831

This procedure allows you to create multiple sites sharing one common set of Drupal core modules, and has been tested on Windows XP (SP2), Apache 2.2.3, MySQL 5.0.24a, PHP 5.1.6, Drupal 5.2..... I'm assuming that you have a working Drupal installation already.

1. Create a new MySQL database with appropriate rights.

    eg. mydb

2. Create a new folder in your sites folder by copying the default folder and then renaming it with the name of your new site.

    eg. mysite

3. Create the following sub-folders in the above folder for stuff unique to your new site.

    mysite\files
    mysite\modules
    mysite\themes
    mysite\tmp

4. Edit the database and base URL in the settings.php file in the folder you have just renamed.

    $db_url = 'mysql://username:password@localhost/mydb';
    $base_url = 'http://mysite'; // NO trailing slash!

5. Create a new host in the Windows XP hosts file with same name as new folder.

    127.0.0.1 mysite

6. Create a new Virtual Host in the Apache httpd-vhost.conf file with forward slashes in the full pathname (include <> tags as per the examples in the file).

    VirtualHost *:80
    DocumentRoot "C:/Program Files/xampp/htdocs/drupal"
    ServerName mysite
    VirtualHost

7. Restart the Apache server to load the virtual hosts.

8. Point your web browser at new folder and install drupal.

    http://mysite/install.php

9. Create your first user and Administer the File System paths to match step three above.

    sites/mysite/files
    sites/mysite/tmp

You can use the Windows Search to find the above files if your not familiar with their locations.

Good luck!

tomado de

http://drupal.org/node/166831