Wow. Sounds like your screwed bro. The clicking noise is the worst, seriously. Opening it probably won't help and will more likely hurt it since you're not a trained professional. I work on computers for a living and would never open a hard drive with data on it that I intended to keep.
Plug it in, boot up. If it works, yay. If it doesn't, bummage.
Don't open it up unless you REALLY know what you're doing. I say this because the platters CANNOT get ANY dust on them, or you'll get a head crash (dust will disrupt the actuator, causing it contact the platter, destroying it). Or, if you know it's fried, disassemble it for fun.
Remember this adage:
Hard Drives are mechanical, making them slower, less reliable, and more fragile than chip-based storage.
Edit: To TC: Yeah, that clicking is probably a f***ked actuator.
the drive is roadkill
the ticking noise, is actually the read-write head that can't focus on the data any more, try to recover with some software, like getdataback, to recover as much as possible, but place the hard drive inside your computer on a IDE channel. good luck, you're going to need it
my freaking mom dropped my harddrive while it was in a external case
it makes a clicking noise and doesnt mount!!!
I did a similar thing many years ago with an old WD 4GB HDD. I didn't need the data on it anyway, and it wouldn't work properly, so I took the cover off and could actually see the head actuator and the platters moving... I was running scandisk which would lock the PC at about 50%, so when it got to about 48% I *gasp* rubbed my fingers all over the exposed top surface of the upper platter as it was spinning.... When it locked up I just pulled the cables out of the back of it while the platters were still spinning... Really awesome gyroscope effect! Much stronger than I would have thought! Then I took the whole thing apart... Fascinating!
A very good friend of mine once told me the best way to recover data from a hard drive was to rub my feet on nylon carpet for 5 minutes and then stroke the delicate "underparts" of the drive lovingly for a few seconds. I never managed to get that to work, though... So I never did manage to recover the pictures of him and the sheep. And the horse. :?
Did we mention that most hard drives have at least a 3 year manufacturers warranty? If you haven't voided the warrany by breaking the seal and opening the drive, then you can probably RMA it, and save yourself some money. Check the date of manufacture, and go to their website for details.