not being a wise guy but the old mini will have 500gb or so this machine can use a 2tb drive.
I have an older version a ds110j works very nice. I link 4 mac minis and a diy pc to it and it is a good piece of gear. I have a 2tb samsung in it.
there are lots of ways to get it to work with all 5 machines. If you are all mac it will work if you are all windows it will work. If you are windows and mac if will work. it works with windows 7 snow leopard and lion. my main use is to move all my tv shows recorded on eye tv from comp. to comp.