Use Ubuntu Server or CentOS for your home NAS with RAID 5.
Use Ubuntu Server or CentOS for your home NAS with RAID 5.
Consider using Windows Server for reliability and backup capabilities. It offers better performance than Win 7 and supports multiple drives. Your hardware is suitable for a server setup, though you may want to upgrade RAM if needed. A Z97 processor is adequate for this task.
R2 Essentials is currently priced at $399 on Amazon, but you might be able to get a more affordable option.