hard drive failure????

[mccompunerd]

aight, i've got a friend that has the following system specs

gigabyte socket 370 board
p3 1.4
512mb ram
wd 120gb
winxp pro sp1

mkay, one day he's playing some game, and the computer freezes, he goes to reboot, and when it tries to boot from the hard drive it gives this error
"Failed to load operating system"
now, thinking it might be the hard drive, i grab a 40gb that he has in another system(linux) and drop it in, same thing... what in the world would cause that? the drives spin up, are detected by the bios, but just will not boot... he has another board that's brand new, so we drop the proc. in, and try the 120gb on it, no go, says it isn't a valid boot disk... tried installing xp on it 3 times, and still the same thing on the reboot... ran the wd utilities, and even low-level formatted the thing, no errors detected... if anyone has a clue, please let me know.... in the event that the drives are dead, and even if the board is dead, no big deal, it's just buggin the hell out of me all day.... thanks in advance for any help that may be offered, and even if y'all don't have a clue, thanks for reading my rant :D

[Tweaked!]

I would have to say that if it successfully ran a LL format with no errors, then I highly doubt it's the drives. A few other things to check, clear the cmos, changeout the ribbon cable going to the hdd, swap around the 12v feed lines going to it, and run chkdsk.