Platypus, it's OP's second post that answered how the ext HD is connected [via USB] and that OP wants to SHARE that drive so that all computers can see it.
I should have guessed it from OP's first post, never have been "the best" at guessing!
You raised a great point! For a few weeks, I did have a full blown Windows XP on a used laptop within my Windows 7 Professional "network."
Most of my computers' "seeing" each other drives were one-way, the XP did not work well at all reading/writing to Windows 7's controlled HDs.
The Windows 7 computer could most of the time read from/write to the Windows XP controlled HD. Many times, there was problems coaxing the reads/writes.
OP needs to tell us what OS computer Number One is using [by Number One, I mean the computer being post/booted first, the computer designated as The Firsrt.] Getting OS X communing with OS Y is not always easy! Home and small business-based networks often have a Number One -- that's the advice I got from a local computer guru. OP needs to tell us how computers are using Windows XP, how many are using Windows 7, or whatever OS.
Also, are all the computers "hard-wired" [Ethernet] and/or "wireless?" Hard-wire and wireless was not mentioned in OP's opening post.
Platypus, correct me if I'm mistaken, I'm thinking: OS differences [unless ALL are Windows XP] and whether Ethernet-hard-wired and/or whether "wireless" absolutely plays a part in not only initial setup but also absolutely plays a part in the day by day operations of shared drives.
Edited by RolandJS, 11 October 2015 - 07:17 AM.