DIY a NAS + HTPC.

Ok, I just upgraded my main gaming PC. took a look at my cabinet and realise i have a few un-used items for me to play around with.

Thus i came up with the idea of a HTPC + NAS system.

My setup:-
GA-965p-DS4
4x 750GB HDD.
1x 120GB HDD for OS.
Leadtek 7950GT.
C2D E6600
Kingston PC800 ram.
Window 7 enterprise.

(i am only lacking a case)

Basically another PC by itself. but its main use its just to play/ stream HD videos (i have a apple tv/xbox360, but it doesnt stream subtitles unless i do encoding which is a pain in the ass, i dont like tversify ), run Bit torrent 24/7, NAS with raid 5 for simple data protection.

I am going to connect this directly to my 42 inch LCD TV in my living room. Maybe even add a blueray drive in the future as i do not have a blueray player currently.

However, i am a total noob in RAIDs and i noted in a few forums that power consuption seems to be the major issue in NAS setups, which i think mine will be a total failure since its basically another PC by itself. Is there any setting for window 7 that could help with it? But if i am running BT 24/7, its not going to help with any HDD idle setting does it?

Just wanted some feedback, tried not to beat me with a stick for my idea but i simply just wanted to use all this spare parts that i have with me.

Also, any proposal for my raid setup?
My intention is to do BIOS raid5 + windows 7 for OS.
Is there such a thing as window raid?
Do i need to install things like the Intel Matrix Storage drivers or programs?
Is this idea bad? better off if i get separate items like a buffalo quad nas? and a commercial HTPC?

Well, NAS means Network Attached Storage, so first off you are not talking about NAS. You are talking about a Media PC with a RAID array. Which is perfectly sound. However you may need to change your operating system, I'm not sure of the streaming content capabilities of Win 7. Drives that run constantly consume power, nothing you can do about it. Your motherboard doesnt' appear to support RAID, so you will need a RAID controller card installed. This would be hardware RAID. Software RAID is possible but I do not suggest it. Performace concerns with RAID will be your read performance, therefore you need a RAID solution that meets your streaming requirements as well as your data security/integrity needs. For lots of media you need lots of space, so maximizing capacity is probably good, in this case I guess RAID 0+1 with your 4 drives is probably best. Basically stripe 2 drives to 1.5TB and then use the other two for a mirror.