Problems with SATA drive

[Altria]

Hello All,
I have just finishing building a personal PC with Win XP. I installed the OS
on the SATA drive but during boot-up it tells me "Invalid System DISK,
Please replace". Now here is the point that gets me....when I change the
boot order in the BIOS to CDROM first and place the WIN XP CD in the disk
boots fine (after it passes the stage of Press Any key for setup). I am
under the impresion that DOS is unable to recognize the disk, or missing
NTLDR. Is there anything I could do to fix this?
TIA,
Altria

 

[Jerry]

Could be the Primary partition on the SATA disk has not been made Active