Wow! What a pain-in-the-ass! I just finished networking a Macbook Pro and a Windoze Vista laptop to an Ubuntu desktop. It was my first experience with Samba, Webmin, and networking on a Mac. With the help of this howto and a lot of "hope," I finally got it figured out.
Three days and a bottle of migraine medicine later, I can now stream movies from my old, nearly worthless PC, to my shiny new Macbook. That's right, I wasted about 5 hours of my life reading, installing, uninstalling, configuring, and cursing just so I could map a drive on my Ubuntu desktop over the network to my Macbook ... oh, and I went ahead and did the same for this piece of shit next to me running Vista. I started to network my Eee PC as well, then I decided SSH is so much easier and put it away. If you're curious about the title of this post "OSx -> Ubuntu & Vista -> Ubuntu," I didn't network the Mac and the Windoze machine together, mostly because I didn't feel that machine needed access to my Mac files ... that's what Dropbox is for.
I'm not going to go into specifics, mostly because I forgot most of what I did (just look at the 'howto' mentioned above if you're interested). Surprisingly, mostly because I'm still new to OSx and learning it, the easiest part was the Macbook, all I did was open Finder where my network drive was already listed, clicked on it and away I went.
Anyway, now it's time to celebrate with a beer.

