You have recently replaced your motherboard and now that you try to boot up, it cannot detect your serial AT attachment hard drive now. You have been trying to boot off of a Windows XP CD, but says it cant detect a hard drive. You have unplugged all cords and put them back in, but still no progress.
Try going into that computers Basic Input Output System to make sure that your computer is detecting your serial AT attachment hard drive. Power on that computer and immediately keep tapping a "Tab" key, DEL, Delete key, or whichever key is necessary to get into that basic input output system. Try this configuration in that basic input output system. Go into a basic input output system, then choose "Integrated Peripherals".
Set settings in that menu option to:
Chip ATA Operating Mode: Native Mode
ATA Config: PATA + SATA
SATA Keep enabled: yes
PATA Keep enabled: yes
PATA channel selection: both
Set SATA as RAID: No