So I have two hard drives and two DVD drives, and I wanted another hard drive. I got a SATA one, and installed it just now, but Windows doesn't recognise it. What to do?
If you have "two hard drives and two DVD drives", then you added a SATA drive, I assume the 4 former devices are all IDE and are run on 2 IDE drive cables.
So we check the BIOS to see if the SATA interface is turned ON, and if it then detects the SATA drive. If not, then you've got problems:
1. Is the drive good? Is it new? Does it seem to power up when the power plug is connected?
2. Check the SATA cable for damage. Try another one if you have one handy.
Once you determine that the BIOS has the SATA on and the drive seen, then just boot into Windows (XP, I assume) and check hardware devices for a SATA drive interface. If it's not there, then of course you can't see the drive.
If the SATA interface is loaded by XP, then there's no reason why the disk manager wouldn't see the drive.