New Server Build ~ Need opinions

Hi, I am currently in the process of picking out my parts to put together a home server for streaming video and files etc. I have a small list of parts and just wondering if anyone would car eto cast any opinions / criticsm on my build as I would love to hear your thoughts.

Note: I am building this to be small, semi-cheap and large storage/decent transfer speed. It also will be on for most of the day/ multiple days at a time. For this reason I will most likely be using RAID 5 or 6 just for data protection and drive failures.

Here is my working parts list. (also note, no keyboard or monitor. I will be ftp or remote access only and OS install from a bootable usb)

Case: Lian-Li Mini-ITX

Mobo: AsRock Mini ITX usb3.0 etc.

PSU: Silverstone 500W

CPU: Intel Celeron Dual Core

RAM: Kingston 8GB DDR3

Storage:

3x Seagate Barracuda 3TB 7200RPM

1x Seagate Barracuda Green 1TB 5900RPM

Cooling and other parts will be determined after core build is decided.

So what do you guys think? Again not the most powerful of machines, but it really is only for storage and streaming video. I really have never built a server PC before so any feedback would be appreciated! THANKS!