Deepak3i is right. You need to load the driver for the SCSI adapter during the Windows XP setup process. Find the Brand and model number of the SCSI adapter. Download and uncompress (if needed) the driver files, then save them to a floppy. One of the first questions Windows setup asks (at the bottom of the screen), is if you need to load additional drivers. At this point in time, press the F6 key, you will not get confirmation if you pressed it in time or not. When Windows is ready to copy files, it will detect hard drives available to it. If it cannot detect an IDE drive, it will prompt you for a driver disk (assuming you pressed the key in time during the start of the install). Once Windows loads the adapter driver you provided, it can then see the SCSI disk attached to that adapter.
Good Luck