I can make a comment about BD support. BD player needs XP or higher, for I have win2000, and it's not supported. I doubt ws2003 is either. Ubuntu I am not sure of (but I have my doubt).
I just started building my HTPC. It's a Gigabyte MicroATX board with a P4 dual core processor. 2.6Ghz. I have access to free copies of Windows Server 2003, 2008, and Linux distros of course. Right now I'm dual booting with Ubuntu and WS2003 (use WS2003 for class). But I'm confused on hardware to obtain to do what I want.
I'm basically trying to use this PC to replace a set top box. I'll be using it with DirectTV and I'm not sure if I can obtain the hardware to tune channels or not, but I'd like to be able to use it as a DVR. If not, then I'd just like to use a TV Tuner card to record over the air stuff. Then I'd like to watch DVD's, Blu Rays, music and all that stuff. So if anyone has any experience with this, please let me know. I've been searching and it's a little difficult to gather all the info that I need to make hardware choices.