New Graphics Card for HTPC beneficial or not?

[bindo]

Hello,
I've got a bit of an antiquated HTPC which deals with normal TV rips and films just fine, however stuggles with any HD content above a few Gb in size.
Rather than upgrading all of the hardware my first thoughts are with buying a new graphics card which can handle dxva to offload the HD processing from the CPU.
But I'm not sure how successful this would be or which card I would choose if it would work out ok.
At present the PC specs below will play some HD rips for a few minutes, but will then start stuttering or the audio will loose it's tracking with the video, rendering most films unwatchable!

My HTPC specs are:

AMD 4000+ (Socket 939 @ 2.41Ghz)
Asus A8N-SLI Deluxe
1Gb Generic Ram
X800GTO2
Corsair HX520 PSU
Silverstone Lascala LC17S Case (HTPC - Full ATX)
Windows XP - Media Centre 2002 Edition
Samsung 40M87 (1920x1080)

The PC is only used for watching online streaming content (iPlayer etc), TV shows and movies (BD Rips etc).
Link 1.
Link2.
Link 3.
The three links above were some quick ideas I found from searching on two sites, would they be suitable?
The card would have to be passively cooled as I am currently trying to make the PC silent and preferably below £50.

Alternatively what sort of budget would I be looking at to build a basic PC to run the HD rips?

Any advice would be great.

[CAT-THE-FIFTH]

The first card should do the job and also an upgrade to 2gb of RAM would also help.

The single processor should still be fine TBH once the graphics card offloads most of the decoding.

[mac124]

I had a 9500gt in my htpc for a while and it worked like a charm, i played BD disks with it just fine, never loading the cpu (x2 5200) much above 25% so can recommend one of those.

As mentioned more memory might help too.

[scaryjim]

Franky, for decoding purposes a HD4350 would do just as well and save you a few £££ - ebuyer have a passively cooled HIS model for just £23.83 - bargain One word of warning - make sure that your playback software supports hardware acceleration before splashing the cash!