Plz, Help me pick a PCI GPU (with VDPAU, for future MythTV release)

I am building a MythTV system at my house (on the cheap) using Mythbuntu and 2 used pc's I picked up for short $:
2x Compaq Evo D510s - 2.4ghz P4, 1.5GB RAM, 500GB ide HD
1x HDHomeRun - To capture HD QAM channels from my cable company.

Now all I need is to purchase a PCI video card that will support VDPAU [wikipedia] [mythtv wiki].
Yes I realize that VDPAU is still in beta, and I would have to build MythTV in order to take advantage of it now (which is not my intentions), but I would rather purchase a card with VDPAU support now so when MythTV .22 is released w/ VDPAU support I will be ready to take advantage of it.

So I've narrowed it down to these cards: (click on the image to go to the NewEgg.com comparison page)

They are all similarly priced, 4x8400GS's & 1x8500GT.
Can someone please help me with this one, I don't know which to choose.

One important factor that is going to play into this is the fact that the Compaq Evo D510s's PSU is only rated for 220watts, and 2 of these video cards list 300watts or better PSU required. I plan on disconnecting the D510s's CD & Floppy drives once I get Mythbuntu installed, hopefully this will free up some room for me to run one of these GPU's.
There is a review posted on the PNY card that states that someone is using a 250Watt PSU and it runs fine for them, so I guess I could use that?
Because of this limitation, I will only buy 1 GPU for now to test on one of the machines, and if it works I'll buy a second.

p.s. this is a continuation of this thread: Building Myth System on the cheap, recommendations?

You'll want something with 512MB of dedicated video memory so you can get good playback with high reference framed HD h264 content such as L5.1 compliant video. Just as a note, Nvidia is still working on smoothing out some of the kinks with VDPAU and L5.1 compliant video, so get the latest driver updates as they come out. Really though, I'd recommend a card with at least 512MB of dedicated memory, and a 128-bit memory bus. I'd go with something like this when it comes back in stock:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814187057
You don't have too many options with a PCI interface. That's about as fast as you'll get.

Also, most PCI cards don't support hardware acceleration/it's completely borked.

Replace the mobo if you can cause thats the only way you'll be able to do what you want with it.

w1retap said:

You'll want something with 512MB of dedicated video memory so you can get good playback with high reference framed HD h264 content such as L5.1 compliant video. Just as a note, Nvidia is still working on smoothing out some of the kinks with VDPAU and L5.1 compliant video, so get the latest driver updates as they come out. Really though, I'd recommend a card with at least 512MB of dedicated memory, and a 128-bit memory bus. I'd go with something like this when it comes back in stock:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814187057
You don't have too many options with a PCI interface. That's about as fast as you'll get.

Click to expand...

Thanks for the help w1retap,
Is it worth the wait for the 9400GT (that you mentioned) to come back-in-stock, or will I be able to get by with the Sparkle 8400gs w/ 512MB?
Also I find it odd, but the MythTV wiki [supported cards] doesn't like the 9400GT as a supported card for VDPAU ???

CrimandEvil said:

Replace the mobo if you can cause thats the only way you'll be able to do what you want with it.

Click to expand...

I wish this was an option CrimandEvil, but the purpose of this build was to do it on the cheap... I purchased both machines (Compaq D510s) for only $60. If I was going to replace the Mobo, I probably would've gone a completely different route.

Well, you should have gone a completely different route. Buying lowend, crappy, limited hardware for cheap with the hope of building an HTPC isn't a very good route. The 8500GT is the best option but it doesn't do full hardware acceleration of H264 material so you'll need a decent CPU to make up for it... and this is all best case situation with a PCIe version of a 8500GT.

The PCI versions don't do complete acceleration....Wait. A D510? Yeah, you have a ways too go since those are terrible for HTPC usage. The hardware is terrible.

I'm going to have to agree here. I wouldn't waste even more money for something that most likely won't work how it should. Maybe give one a try and see how it works out, but I wouldn't get expectations too high.