Digital TV for mac laptop and pc


I have a powerbook g4 12" and also happen to own a soon to be upgraded pc desktop, its all good, and almost everything works across both platforms, however i have decided to invest in a digital tv tuner, and would prefer if it would work with both machines, preferably a small bus-powered one so it could be used on the road. I havent been able to find a unit that works with both mac and pc yet, but i have heard of an open source project that allows you to use any hardware... any ideas on what might be a solution, anyone heard of this software, or any ideas on some hardware that i havent come across?