Question Setting up a Raid 6 Media Server

It's come to the time where I have so many hard drives in different PCs all littered with media, including duplicates, that I think it's time I made a media server.

Only question is which way to go?

I dont have enough money for a full 1-1 backup, which is what I think Raid 10 does. So I'm thinking about Raid 6, that way if one hdd dies I can easily change it.

I want a separate OS hdd.
Also not sure, can software raid on my motherboard do the job, or should I get a raid controller card?

Any links to tutorials would be appreciated, as well as suggestions.

Also window or use something like FreeNAS?
Thanks

On a side note, I current have a ReadyNAS Duo, it's just 2 drives, but what I hate about it and didnt know when I bought it is that first of all I cannot just remove a hdd and plug it into another hdd because Netgear use their own format which windows cant read.
Not only that but but if the ReadyNAS breaks down, you cannot simply buy another one and put your drive in it so if the device dies, you lose everything!
So I'm not looking for such drawbacks for my server