776
I'm not even sure how many chickens I can fit on my current hard drive, but it's probably more than the number of persons I can fit.
Alright, let's do some math.
According to a quick search, chicken wire weighs about 0.07537 lbs/ft^2 (sorry for using yeehaw units). When building a chicken run, you need about 10 ft^2 of ground area per chicken, which will use around 50 ft^2 of chicken wire, give or take. This comes to 3.7685 lbs of chicken wire.
Another quick search shows the average hard drive is about 1.38 lbs, which means the average hard drive has a capacity of only 0.366 chickens. Which makes the 1 chicken capacity drives quite competitive, really.
Just be careful, it might weigh your case down quite a bit.