Have you reinstalled XP? If you are able to boot with this drive on another PC that means that the hardware profile that XP has stored does not match the PC that it is in and would give you issues.
Which would require either a Repair install or a reinstall of Windows.
Bug Check 0x7B: INACCESSIBLE_BOOT_DEVICE
The error you are getting is a inaccessable boot device which could also point to the fact that the boot information on the drive does not match that of the system.
If this was used as a 2nd drive in another system and is now the only drive the boot information would be incorrect and would give you this problem.
More than likely you will need to do a repair install of XP to fix this.
How to Perform a Windows XP Repair Install