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Microsoft Resource Kits - Windows 2003 Resource Kit

Diskuse.exe  (Windows 2003 Resource Kit)

The Window Server 2003 Resource Kit is a set of tools that system administrators and engineers use to manage or support a Windows Server 2003 system. Use it to streamline management tasks such as troubleshooting operating system issues, managing Active Directory, configuring networking and security features, and automating application deployment.
Diskuse.exe
DiskUse is a command-line tool that scans directories on a hard disk and reports on space used by each user. This tool can scan a single directory, a directory tree, or an entire drive and can extract information on one user or all users. Reports can be displayed on-screen or output to a file, in table or text format. DiskUse can also list all the files owned by a user or users, filtered in a variety of ways