I eventually came across with a very facinating software called Plex. It’s a media center application for Mac OS X (Leopard only), based on the famous XBox Media Center, which is nowadays more or less outdated and not available anymore (see http://xbmc.org/). I found this application when I was trying to watch some HD material on my Mac laptop.
I have some experiences on building HTPC to Linux platform, our current TV recording solution is based on Linux machine and VDR. Well, installing this Plex application on Mac wasn’t really that interesting than building the application from source code with proper Open Source style. Instead, this was indeed a Mac application, just a drag to Applications folder and it was ready.
I have to say that installing and trying this software was some sort of mistake. I had downloaded couple of HD trailers (1080p, H.264) from Apple’s web page, and had tried them with QuickTime Player and VLC. Neither of these players was capable of playing the trailers smoothly for some reason, but the Plex let me speechless. The picture was sooo clear, without any breaks or jumps or other nasty things. The quality for example in David Gilmour’s (Pink Floyd) live trailer was totally astounding. Of course playing full HD video isn’t that easy job for CPU, playing the clips takes more than 100% of CPU time, but that’s what the CPU cores are for. It was also remarkable that the application is rather easy to use, and seems to have very much features.
Well, why it was a mistake to try Plex? Simply because we have a crappy 26″ tv with very poor picture quality. But now I’m afraid that there is no turning back. I just tried to watch a regular digi-TV broadcast, and it almost made me feel sick when thinking what I just experienced with HD material (and I was watching the trailers just on my laptop’s screen). So, a proper screen with Full-HD capablities will be my wish to Santa Claus. And of course, to have something else to watch than just trailer clips, a Blu-Ray player or drive for Mac would be a nice surprise 
I hope that the global financial crisis has not affected too much at the Santa’s house.
Just a note. XBox Media Center is not outdated and forgotten: http://xbmc.org/
(and works on linux,windows and (intel)mac) .
I’m running it on my HTPC side by side with mythtv.
Plex is also limited to intel macs. Our poor little PowerbookG4 is not able to run it :/
Thanks Ilja, I stand corrected. I had an idea that the original XBMC was available only for XBox, which most likely can’t play HD video with the original hardware, I guess.