These custom install.dat files are necessary to run NBA Live 2000 in newer versions of Windows. As the 16-bit installation routine will not work in 64-bit Windows, this file will not be created as normal when copying files from the disc. The custom install.dat files will let the game know your optical drive letter, and that all game files have been installed.
Installation
Open the .zip file that matches the letter of your optical drive (eg D:), and extract the install.dat file to your NBA Live 2000 folder.