|xbox hdds have a locking code that prevents them from being swapped for other disks and to protect the users data.|
Most xbox hard drives can be unlocked and used with a pc but you will loose all of the xbox data on the disk. It also probably won't be usable again in the xbox without entering the special unique key unless you have the right kind of mod chip.
I actually have unlocked a western digial wd80eb-28cgh2(8gb) from an xbox, the unlocking technique baffles me but it worked.
Are you sure it's an 80gb not an 8gb? I believe than most xbox hard drives are around the 8gb mark(from web searching) and my drive confirms this.
You will need to find the model number and brand of your drive if you want to try to unlock it.