Question : Problem: Recovering Data form a Corrupt HD/MBR

Over the weekend I had my hard drive on main PC (running Windows XP Pro) lock up.  When I rebooted, it went into Check Disk, which locked up as well.  On the second reboot, the HD was no longer found.

I pulled the drive and placed it in my 2nd PC (also running Windows XP Pro) as a Slave.  On boot up, the BIOS did recognize the type and size of the drive, but once I was in Windows, I could not access it.

I did manage to access it with a Hex Editor, and did find that the MBR was scrambled, and could not detect the drive partition.  I also received many Sector errors as well.

My question is, what can I do (other than FDISK /MBR, which did not work) to rebuild the MBR and/or save the data from the drive.  Preferably, while still in the other PC as a slave, as I have already purchased and configured a new HD for the PC which it came out of.

Answer : Problem: Recovering Data form a Corrupt HD/MBR

Did you try replacing the data cable with a newer one, with blue ends and a "higher density" ribbon?  
These are the new multi grounded cables for higher data throughput -- the Cable Test error suggests to do that.
Also, when you pull the data cable off, check all the pins on the MB and the drive carefully for bends or cracks.
Try the drive on the secondary controller just to test.  Maybe the primary went bad.  Try all these ....