Mark Russinovich at www.sysinternals.com has released the freeware utility Sync which forces NT, Windows 2000, and Win9x to flush buffers and save unsaved buffered data. Useful to Windows NT admin.

UNIX provides a standard utility called sync, which can be used to direct the operating system to flush all file system data to disk in order to insure that it is stable and won't be lost in case of a system failure. Otherwise, any modified data present in the cache would be lost. Here is a an equivalent that I wrote, called Sync, that works on both Windows NT and Windows 95/98. Use it whenever you want to know that modified file data is safely stored on your hard drives. Unfortunately, Sync requires administrative privileges to run. This version, 2.0, also lets you flush removable drives such as ZIP drives. Source code to the NT-only version of Sync is available on the Dr. Dobb's Journal Systems Internals CD-ROM

New Riders has good NT texts.