Yup, sounds bad. You can indeed slave it to another HDD, though if it's not being picked up in the BIOS, then it's likely very dead. Here's some more basic stuff to check:
Check the IDE cable for creases that go counter to the thread of the wires, or even dents. If there are any of these there's likely to be a slice through one of the wires inside and that's your problem.
Have a look at the IDE socket on the HDD and on the mainboard. If there are any pins out of place, GENTLY try and bend them back with a small flat head screwdriver.
If the HDDs making noises like an optical drive it's pretty dire, but then some HDDs can be real noisy. If you do manage to get it picked up in BIOS setup, then you should probably backup all the important data (if you have any) by slaving it as suggested to another HDD and simply copying it over. If stuff is missing you can download like PC Inspector File Recovery. I don't know a URL off the top of my head but that app works for us at work though it's not perfect, it is simple to use. There may be a restore package in the download section here in fact.
Hope you have some success.