Storage FTP server and raid

[donok]

i am planning to build a nas drive that can be used as a FTP sever to allow file backup. I would like to use raid 5 with 6 drives

i have 5 pc users 4 of which are away from home that need to be able to access the server. i would like 5 people to be able to connect to the server when at home via ethernet or wifi and when there away from the home, preferably by using logins and passwords

we also have a smart tv for which i would like shared videos to be able to connect to allowing home videos to be watch from it.

i think i have the hardware sorted

- pentium g630
- msi B75MA-p45 motherboard
- 2gb corsair ram
- silverstone precision case
- corsair 430w psu

total price - £180

i am thinking of using 6 or 5, 3tb hard-drives to create a large array. what i would like to know is what operating system should i use for my needs ? and how complicated will the setup process be ?
is the hardware i have selected correct ? do i get a dedicated raid card ?

[donok]

another option would be to get my old dual core e5500 pc and just drop a reliable psu, passive gpu and
dedicated raid card.

or just get this

http://www.scan.co.uk/products/qnap-...-4xusb-2xesata