First off, if you want to use either the DMA21 or 2200, you better hurry as Linksys have discontinued them.
Tv pack is lush to use, but not necessarily all that reliable. See
http://www.pprune.org/computer-inter...e-experts.html
However, if you don't trust it, then take a disc image of your os before installing it & then if it doesn't work for you, simply restore your pre-tv pack system. That or install it on a fresh, non critical hdd, so as you can play with it. You cannot uninstall tv pack once it's in Vista...
Win7 has native h264 support. I believe tv pack in Vista can be hacked to support h264, but don't quote me on that. So far it's all saying win 7 huh?
I have always used Hauppauge cards & found them just fine. As always be sure to do your reading before you buy as mistakes are easily made. For standard def Virgin boxes for example, the digital signal is converted to analogue output by the stb itself, so you must use an analogue tv card such as the HVR900 to process the signal. Also, if you intend to use the card to record shows whilst also watching something on another channel, you must use a dual tuner card & I'm not sure if skyboxes permit that or whether you would require a 2nd sky stb hooked up to allow simultaneous channel processing.
I have a DMA2100 over a powerline network & it's just fine for streaming tv. However, I have read that users have struggled to get enough bandwidth to do same with HD streaming. Again a bit more reading will determine the best route. Certainly a wired rather than wireless network will give better performance. The DMA2200 does support H264 though. Of that, I am certain.