This is a WinNT/2K/XP/03 installation driver disk (i.e. you use it by pressing 'F6' at the beginning of the procedure) for the Silicon Image 3x12 SATA chipset as used on the Asus A7N8X-E Deluxe motherboard.
Download this file, unzip it, and copy the files to a FAT-formatted floppy disk (not the directory, just the files).
sil3x12.zipSee also: this page.
If this driver page was useful to you, please drop me a line so I know to keep it around.