Microsoft Knowledge Base Article 841290 contains the following summary and introduction:
SUMMARYThe File Checksum Integrity Verifier (FCIV) is a command-prompt utility that computes and verifies cryptographic hash values of files. FCIV can compute MD5 or SHA-1 cryptographic hash values. These values can be displayed on the screen or saved in an XML file database for later use and verification.
INTRODUCTIONThis article discusses the File Checksum Integrity Verifier (FCIV) utility.
Warning The Microsoft File Checksum Integrity Verifier (FCIV) utility is an unsupported command-line utility that computes MD5 or SHA1 cryptographic hashes for files. Microsoft does not provide support for this utility. Use this utility at your own risk. Microsoft Product Support Services (PSS) cannot answer questions about the File Checksum Integrity Verifier utility.
The File Checksum Integrity Verifier (FCIV) utility can generate MD5 or SHA-1 hash values for files to compare the values against a known good value. FCIV can compare hash values to make sure that the files have not been changed.
With the FCIV utility, you can also compute hashes of all your critical files and save the values in an XML file database. If you suspect that your computer may have been compromised, and important files have been changed, you can run a verification of the file system files against the XML database to determine which files have been modified.
The FCIV utility runs on Microsoft Windows 2000, Windows XP, and Windows Server 2003.