If this computer has suffered from many virus infections, theres nothing to say that those viruses did not infect the BIOS chip or other flashable devices firmware in the process.
I would take it that the devices are being detected by the motherboard's BIOS utility.
If this is the case, the hard ware would show up under PRIMARY MASTER and PRIMARY SLAVE as well as SECONDARY MASTER and SECONDARY SLAVE.
Are you at least getting these devices to show up properly in the BIOS?
Also it is NOT always possible to install an OS on one computer and succesfully move the drive to another computer and have the hard drive boot up properly, at least NOT since Windows XP and the other NTFS operating systems came along. So this may have worked before, as you say, but it does not work in most cases.
You may need to check the condition of the data cables that are connecting the drives to the motherboard.
If this system is old, corrosion from oxidation may have built up on some of the connecters on the motherboard, the data cables may be old and have cross-talk issues or faulty connecters.
Check the CMOS battery and make sure it is good, if its been in the motherboard for years now, it may be depleated of any useful energy.
Check the motherboard over for any possible corroded connecters, use an old tooth-brush to remove any white power caused by corrosin.
Check the power connecters as well, these suffer from oxidation as well.
Thats about it.
Post back the results.
Edited by MrBruce1959, 17 December 2010 - 01:34 AM.