Of-course there's a lot to be said for just installing your distro of choice and just using what you need.
This last is certainly what I'd do, for a headless machine just use something like Ubuntu Server and it takes very little space and can update itself happily for a long time without attention.
Thanks for the suggestions guys.
As it happens I spent some time over the weekend setting up both FreeNAS and OMV in VirtualBox environments.
After that I decided to just build a headless Debian 7 box :-)
Cheers,
Ewan