TWinExplorer

From Pepsoft:

If you'd like to increase your productivity when organizing the files and folders on your hard drive, try doubling up with TWinExplorer, a cool utility that places two instances of Windows Explorer in a single window. The program works double-duty for you by running as a standalone application, leaving your Windows 95/98/NT shell completely untouched. With its intuitive toolbars, TWinExplorer makes easy work of renaming, copying, comparing, and moving your system's files and folders. Retaining the standard functionality of Windows Explorer, TWinExplorer also boasts features such as file-type filtering and single-click access to your favorite folders. In addition, the program's panels can be quickly resized, and there are handy buttons for refreshing folders, creating new folders, and file searching.