Server Able To See Other Machines

Hello - I have my ubuntu file server up & running...First time for me, but has shown itself to be very dependable thus far. I have a couple of windows machines on my network as well as one network external hard drive.
What I need help with is, from the command prompt on my server, how can I see the other computers on the network...Furthermore, how can I copy files from that network drive onto my server? I would like to do with this without the involvement of my windows machines (as little as possible)

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I don't even know how to view other the other computers.

Thanks,
~roystreet

I'm not too up on this stuff, but, presumably, since you mentioned windows computers on the network, you're talking samba shares?

As part of the smbclient package, there is a tool called findsmb, which queries the network for samba servers.

You'll also want to look at nmblookup.

There is an ftp-like client, called smbclient, for file transfers, and you can mount samba shares pretty much like any other volume.

Samba client - Linux 101
SMBCLIENT(1) manual page