I need to have theses features :
– network sharing for documents, music, phots and videos
– music stream server, accessible from internet with web browser and smartphone
– download server, something like synology download station
– ftp server, accessible from internet
– web server with php, mysql for possible small web hosting
– possibility of virtualization
– ability to sync datas with other server/NAS
– disks fault tolerance
– disks monitoring
– filesystem snapshots in case of human error file deletion

so good candidates are freenas,nas4free, or go to linux distribution or freebsd release.
I personnally exclude openindiana, and other things based on solaris or opensolaris because I’m more experienced on linux/*BSD and supported hardware is more limited
Also, I exclude microsoft OS (windows server/home server) due to extra cost and feature limited for my need

I decided to go to use FreeBSD 9.1 for OS… I want ZFS and fully setup system like I want

Next step is hardware buy…