You should create a Windows user account for your Sun Java System Web Server. It should have restricted access to your system resources and run under a nonprivileged system user account (one that has a limited set of system permissions to your system). When the server starts, it runs with this user account. Any server extension modules the server uses are created with this user account as the owner.
During installation, the server uses the LocalSystem account, not the user account you created. Once you start and run the server, you should use the user account you created. You can change the user account for the server after the installation process. You can configure that user account so that it has permissions to get files on another computer, so that your server can serve files that are mounted from another computer.
In addition, the user account you create for the server should belong to a group that contains the server users for all Sun Java System servers so that multiple servers can have access to shared files.
It is strongly recommended that you use a dedicated account for the server.