I have been told I could use amarok to play files that are on another computer (hard drive) on the network ....

I seem to have gotten ubuntu to find my Mac, to access it, and, even, to my surprise, it finds the RAID volume.  so I am very cool!

Now I need to try to get that to work with Amarok: I will have to figure out how to tell Amarok how to include music from that "folder" - it took me a while to figure out how to put an external hard drive on the library (under "media," as I know now) so how do I tell it to to include those hard drives (under "volumes") on the Mac?

Once I do that, I know it will take a long time to load it all into the library / collection, but am really excited at the thought of that happening.

Will

http://amarok.kde.org/wiki/Samba should give you the good oil on mounting remote drives so they appear as local directories.
Then it's simply a matter of adding those directories in Amarok's collection setup. If you want the music there all the time (and most people do!) then make sure you see the section "Making the solution permanent".