I installed Windows SharePoint Services, but I can't extend a virtual server

• Is your file system formatted with FAT instead of NTFS?  If you installed Windows SharePoint Services to a disk drive formatted with the FAT file system, your default virtual server might not be extended. On the Microsoft Windows platform, the security features of Windows SharePoint Services require the NTFS file system. Microsoft Windows Server 2003 includes a conversion utility (Convert.exe) that you can use to convert an existing file allocation table (FAT) volume to NTFS without losing data. For more information, see Microsoft Windows Server 2003.
• Does the virtual server exist in Internet Information Services?  Before you can extend a new virtual server with Windows SharePoint Services, you must create the virtual server by using the Internet Services Manager in Microsoft Windows Server 2003 or later. See Windows Server 2003 online for more information.

Note  To perform these steps, you must be a member of the local Administrators group on the server running Windows SharePoint Services.