When I try to install Server 2003, I get an error saying that Setup could not find any hard drives on the system. Any explanations?
It may be that you have SATA hard disk drives, and the controller is not supported. Has XP ever worked? If it did, this is likely not the problem, since XP doesn't natively have SATA support = if it worked, your drive is not SATA.
To troubleshoot, examine your BIOS for an option relating to SATA mode. The options may include "enhanced" and "compatibility" or similar; you'd want to switch to compatibility (essentially makes the drive appear to be ATA, not SATA).
If drive shows up now during setup, you know the problem: you need SATA drivers for 2003. Note that if you install with controller in one mode you cannot change modes after installing.
Good luck