Most of the popular new PVR cards sold for Windows XP MC, known as "Blackbird", haven't hard drivers to use with Linux/Myth.
We have been working on these drivers and released an alpha version at http://plutohome.com. Pluto even has a self-booting kick-start CD that will automatically install & configure everything for you, including a ready-to-go Myth system. It's the fastest and easiest way to get a MythTV PVR up and running, and also installs Xine, Asterisk and our own software to give you the most advanced media & entertainment, home automation, security, telecom & computing system, controllable with your Symbian Bluetooth mobile phone, as well as PDA's and Webpads.
We're working hard to harden the drivers as quickly as possible and would like as much feedback as possible. These 2nd generation cards are lower in price and offer better picture quality than the current models supported in IVTV, so be sure to check them out. A list of all the compatible cards, known as "Blackbird" cards, is found on our website.