With 7 installed fresh on a totally separate drive you wouldn't need to correct any partition table but simply copy XP boot files over, edit the boot.ini file pointing to the sata drive likely being rdisk(0)partition(1) becoming rdisk(1)partition(1), and simply add the new entry for XP into the 7 BCD with EasyBCD. You then change the default boot device from the sata back to the ide since you put 7 there to see that as the default drive.

To protect 7's restore point and keep that as a stand alone OS you would then have the option of booting from a SuperGrub or WinGrub cd for a universal type boot loader protecting 7 from XP. You wouldn't use the repair tools to try to see a second BCD created on the sata since that wouldn't work at this point.