Well, I have some experience with mythtv+ubuntu and digital and it kind of relates. At one time, I had 2 not high def, but just digital tuner cards and only one hard drive. I ran into bottleneck problems when I was recording one digital tv show and trying to watch another, recorded or streaming. Adding a secondary harddrive helped to stop that bottleneck and I was able to record 2 digital tv streams and watch 1 from the 2nd hard drive. Keep in mind that SD digital TV is at least 1 Gig per half hour and high def will be even higher, so read and write speed will be a big issue for hard drives that will store HD tv and movies. So, it would definitely be a good idea to have a second hard drive just for media as more and more media goes high def. That way, all of that hard drive's speed can be devoted to media, as opposed to media+operating system.