Turning old gaming PC into 3D HTPC

[Smite]

The existing hardware:
So, I came on here in 2005 and used your site to spec out an amazing machine:

• Processor : AMD Athlon 64 X2 3800+ w/ 2x512K Cache
  CPU Heatsink / Fan : Thermalright XP-120 Aluminum Heatsink for K8 / P4-478
  Motherboard : Asus A8N-SLI Premium w/ DualDDR400, 7.1 Audio, Dual GB Lan, 2 x PCI-E x16 SLI, Cool-Pipe
  Memory : existing 2Gb PC2700
  Case : Antec P180 Advanced Super Mid Tower
  Power Supply : Antec TruePower 2.0 430W
  Video Card : eVGA e-GeForce 7800 GT 256MB PCI-E w/ Dual DVI, VIVO

It served me _very_ well, and was only recently replaced (mostly due to Final Fantasy XIV's terribly inefficient use of CPU).

Now I want to know just how well this would work as an HTPC / NAS.

My goals for the HTPC are as follows:
1) Expandable storage. Obviously the case is big enough, so I think this is covered, though I'd like suggestions on making a single multi-drive expandable network share.
2) Fast file transfer access. I think this can be achieved through adding a simple gbps NIC.
3) Ability to download files from newsgroups / torrents / etc driven by a web interface. My current NAS runs sabnzbd, so I expect there'd be a windows-equivalent here.
4) Play my media collection. This includes ISOs for 3D Blurays I've authored. I've got a Samsung UN46C7000 that I want to connect to via HDMI 1.4 and have it just work.
5) Play 3D YouTube videos

I have a separate 3d bluray player I can use to play rentals, so I don't need a bluray drive in the HTPC itself.

My thoughts are:
To buy a gbps NIC, a GT430, install my existing windows 7 MCE copy and to call it a day. This makes my wallet very happy, coming in at $55 CAN total.

Any recommendations / concerns / comments?

[Big Pimp Daddy]

I had almost exactly the same spec PC a few iterations ago, so should be able to help somewhat;

1) As I recall, that mobo had about 10 sata ports (or maybe it was the deluxe, I forget), so expandability is not an issue. Regarding software, I suspect some flavour of Linux would be best, personally I find WHS the best for what you describe, but I'm not sure about the feasibility of running htpc apps on top of WHS.

2)Surely the onboard gigabit ports are enough for that?

3) I use the web interface in uTorrent for this; browse torrents on main PC and save the torrent files to the server, all other fiddling can be done through the web interface, as well as watching progress.

4) I have my 7900GT in my brothers PC at the moment (dual core 2.1ghz athlon) and it struggles with 1080p stuff, this might be a codec issue, but sticking in a recent low-end card solves all the problems. I would check on this before you commit.

5) I suspect as above.

And I see you addressed 4 and 5 already, OK. Your plans seem fine, I would question the need for a NIC, but maybe you're having problems with the onboard?

[Smite]

1) I've been doing some research, and I can't find anything in linux that would allow me to play 3d bluray ISOs, so I think I'm stuck with Windows. FlexRAID looks promising though.
2) That's what I get for not remembering my own hardware. That's $20 saved, thank you!
4) I looked at totalmedia theatre and their forums are full of people using a gt430 for 3d playback, so I think that's a safe bet at $35.

[Smite]

So I've gone ahead with this, and it's mostly working beautifully. However I do seem to have one problem.
When switching Windows into 1080p 3DTV res, the TV detects that it's a 1080p 24Hz signal, but only displays a black screen. This stays until the computer reverts back to my previous resolution, assumedly due to a "Would you like to keep this resolution" prompt. 720p 3d mode works perfectly.

The black screen occurs at both 23Hz and 24Hz.

Any thoughts?