Happy Ubuntu server...Yatta!
Pleased as punch, that's me.
I've successfully set up an Ubuntu server on an older Dell box.
I've used the fantastic instructions Here (Thanks, Jon Peck!)
I had to create a new share for torrents, because while I could access the share on OS X, no matter how simple I made the share, Windows wouldn't let me in. But creating a new share - with the exact same parameters and permissions - worked. edit - reason why is below
I've also installed squid, and sarg and webalyzer to monitor it.
I've also installed a small second drive and linked it into my home directory as a test. The plan is to buy a larger drive and use my PC's current drive in the server.
Keen.
I've played around with Ubuntu before, but never had much luck getting it to do everything I needed. I've also toyed with SME Server, Clarkconnect, and the impressive Smoothwall.
The learning experience has been great, and made for a quality geek weekend, and the amount of walkthroughs and tutorials on the web are Ubuntu's greatest asset.

