Help! Boot partition messed up, DISK READ ERROR

[Fiyasko]

Okay so, long story short, I took my buddies old PC's (WinXP) HDD and added to his new hand-me-down PC and tried to add the OS to the new MBR so that he could boot his old OS from the new computer
It didn't work, and after a few partition related tools where i was trying to install a freshMBR so that I could "start over" the discs both now say
DISK READ ERROR when I try to boot them, I've got it plugged in to My computer right now, it's FULLY operational, not even the slightest signs of damage, filesystem is totally fine

How the HELL can I get this thing running? I think the NTLDR and MBR are Both fucked up.
Any ideas? Right now i'm trying to burn a winXP disc so I can try to use the recovery console, but even then, I'm flying blind

Help!, He's super pissed at me for turning his two functional computers into two "DISK READ ERROR" perfectly fine HDD's

[grue]

easy way: plug disk into working computer, recover data, and reinstall windows. if you want to fix the MBR in-place, it will be much trickier.

[jbrnt]

The only thing I could think of is the motherboard not recognising the parameters of the hard disk. This shouldn't happen even with systems built 6 or 7 years ago because all the parameter should be detected automatically. You did say it was an old machine.  

I would check whether the motherboard has detected the hard disk correctly first. Go into the configuration menu of the motherboard and fiddle with the hard disk or controller settings. Reboot and see if you get the correct hard disk size, hard disk brand and model. Replace the hard disk cables with new ones if you have them around.

Do those hard disks have SATA interface or older ATA ones? What are the capacity of those hard disk? Do your motherboard support those capacities?

[Fiyasko]

So, SOMEHOW, the drive was mislabled or someshit (I'm pretty DAMN sure I picked the right one!!!)) and I overwrote my Good computers MBR by telling a winxphome xp to install to my buddies drive, leading to all my drives trying to start the windows setup, rather than give me my OS's

Had to take my machine into the shop and put a Rush fix on it, took the shop 3hrs to resolve *eyeroll*
I feel like such a Failure for being unable to restore my MBR as well as my friends, I'm just smacking myself in the face about the incompatability of the two MBR types (Win7vsWinXP) and how it caused me to land my computer in the shop,

I've now got my buddies machine running a clean OS and his old OS, THERE WAS NOTHING PHYSICALLY WRONG ANYWHERE
This whole Fake "disk read error" that I kept getting was probably from a corrupt NTLDR and MBR, but even then I would expect to be able to Tinker with it without using an OS
Uggh
What WAS the solution? I was trying to add his other OS via boot.ini (two WinXPhome installs) Is that the wrong way to do it?
When adding his OS to the list, it just seemed to ReRoute the boot, and always load the wrong OS
So i thought that it was the MBR, upon messing with it I could only get the machine to tell me "Disk read error" about the HDD
Took it home, plugged it in, all good, no signs of issues, proceeded to install windows, and killed my home machine, In that panic, rather than think "What went wrong?" I thought that I had overwritten my entire OS
Yes, silly of me i know, but with my Main drive booting XP instead of my OS's I had thought that I overwrote and formatted the wrong partition so I paniced

[Bitcoin Magazine]

check to see if you have any USB cables plugged in.  because some BIOSes will look for attached devices (like Android or iPhone).  and if it finds one, will try to boot off it and give you a DISK READ ERROR 

[Fiyasko]

check to see if you have any USB cables plugged in.  because some BIOSes will look for attached devices (like Android or iPhone).  and if it finds one, will try to boot off it and give you a DISK READ ERROR  

*snickers* It was Waaay, worse than that, NTLDR and the MBR were damaged/corrupt by me incorrectley (apparentley) messing with them