A company called Sigma Designs makes cards to do this. Three different models to choose from. Hollywood Plus, Netstream 2000, and X-Card. I recently bought the Hollywood Plus on ebay for $8.
I wouldn't bother with any of those sigma designs cards as I believe they all only do 4:2:0 SD and just about any semi-modern PC can handle that just fine.
As for other better hardware options I know of at least 3. The first I'd recommend is the Roku HD1000 photobridge. This is a networked device that connects to your PC through an ethernet connection. It has an ATI Xellion GPU and can decode 4:2:0 HD at bitrates upto 40Mbits/sec and perhaps even higher. Tsreader can be used in combination with a free piece of software called "cinema Six" that runs on the Roku to stream video directly to the Photobridge via Http. It works quite well. I have one and use it all the time.
Another option is the MyHD HDTV ota tuner card. This card is meant for OTA 8VSB reception and has built-in hardware decoding. It can't recieve DVB-S signal but if you have another card you can use to record to transport stream files it can then be used to playback these files. However, I don't know of any way to stream directly to the MyHDs hardware decoder. Like the Roku, the MyHDs hardware decoder can decode 4:2:0 HD at bitrates around 35-40Mbits/sec.
One other option is the Stradis cards. These are proffesional level decoder cards that can decode 4:2:2. Some models can do HD also and at very high bitrates. However, I believe these are quite costly. Anyway, Tsreader can output directly to these cards. If I could afford it, I'd probably try to pickup one of these cards for 4:2:2 HD decoding, but I'm sure it would be way out of my budget. For the HD models your probably looking at least at a 4 figure price tag.
