If you install XP on a SATA drive you have to install SATA drivers during the setup using a floppy disc or integrate the drivers into a copy of XP, the alternative is to run the hard drive in IDE mode by changing settings in the Bios.
If you have tried to install XP on the SATA drive while you had the other drive in the system with XP pro on it you will have overwritten the boot sector.
To get XP pro running again on the IDE drive follow this to repair the boot sector.
1.Boot from the XP disc and select "R" when asked to go into the Recovery Console.
2.Select the windows installation system you want to repair and hit Enter.You will then be asked for the administrator password. When you reach the command prompt, type the following and then press Enter.
fixmbr
Reboot the PC and it should now boot to the XP pro install on your IDE drive.