I've used Amahi
before. They're good but currently support an unsupported version of Fedora (Fedora 14). There are community attempts at using CentOS instead which are going well but for a little more advanced user.
Basically, what it came down to was me configuring my own NAS using software on Fedora 16 and manually configuring everything.
You should copy the samba, DNS, DHCP, and any other service scripts/configs you use and migrate them to a server in which you manually configure. I've found that to be the best solution.