I have 1 windows pc hardwired via ethernet/LAN to my router and my mbp notebook is wirelessly "connected" to the router.

If I purchased an external storage drive (500gb or 1tb) and connected it to the router (D-Link DIR628) via ethernet or usb (router has both plugs in the back) would I be able to devote half the hd to the pc and half to the Mac notebook? I'm not worried about sharing info between the 2 computers, merely "cloning" each for safety sake in case either breaks/crashes/is stolen/etc. How does this work? I've tried reading up on FAT32 and NTFS but it's all a bit confusing and I've never "partitioned" or "formatted" before either.

If someone could even just point me in the right direction, I'd appreciate it!