I'm pretty new to all of this, so don't flame me too much ok?! I had to do some trial and error, but I was able to watch some 720p MKV files with AC3 on my Co-Star for the first time tonight. For this experiment I installed Serviio 1.0.1 on a Windows Vista 32-bit PC in the house and copied some MKV files, AVI files, and some MP3 files to it to see what I can watch or listen to on the Co-Star. It was a bit of trial and error but I did get it working! Obviously the higher quality MKV files at 720p with AC3 did not work on my HD TV (i.e. Co-Star only supports AC3 as a pass-thru and my HD TV does not have an receiver/amp with AC3 decoding). Obviuously the video would display with the players and it looked great but there was no audio. So after doing some reading and asking some questions, thanks MCD2000 (!), I was able to simply transcode only the audio channels to convert the MKV fiiles which have AC3 to MP3 so they work from this old PC to the Co-Star without problems. A small victory without having to convert any files, etc. I experimented with PlayPoint, which was a little faster and not so laggy, but aVia overall was better and more stable in my simple tests. Now that I can make it work, I want to experiment with GTVBox and maybe Plex to see which offers the best overall features for me. I'm ambitious, but I'd like to take about 75 Disney DVDs, and a lot of older DVDs which I have put away in boxes get them into some media server with the cover art so they kids can easily browse and watch what they want just like with Netflix. That would be cool. I think I have some other media files which also have issues on the Co-Star so some additional profiles may be needed to make these work too. The trial and error saga continues. I may just rebuild that old PC with Win7 x64 to get a little more performance. For what it's worth, Serviio was very easy and quick to setup for my experiment. It took most of the time to figure out the transcoding stuff.