I am using NASLitehttp://www.serverelements.com/naslite-2.php
. I found it best suiting my needs, it has no user authetication so anyone in workgroup can see everything on it. It fits on 64MB USB flash stick so i dont have to use any of my HDDs. It is commercial, like 30$ but its worht every cent, at least for me. I have 1,2TB media on it and as soon as I borrow 1,5TB hdd from my friend I will reformat all my drives on Naslite box and uses LMCE directory structure and let LMCE have full control on it. Speeds are very good for me, on 100Mbit network average is around 75Mbit for me.
Whats Your choice guys?