QNAP TS-509 + Upgrades + PS3 Mediaserver = GOLD
I am using an upgraded QNAP TS-509 Pro NAS (4 GB RAM / Intel E5400 Dual Core CPU @ 2.70 GHz). Recently I've installed the very popular (and free) PS3 Media Server software on it, and WOW! it looks like I have reached the Holy Grail of what a NAS is capable of, because apart from all the stuff that all NASes do,
my QNAP TS-509 running PS3MS also
>>> TRANSCODES and streams 1080p MKVs with DTS sound and Subtitles to my PS3 100% successfully <<<
(besides that, it also streams my complete lossless music collection (FLAC) to the PS3, supports playing .ISO DVD images, supports .CUE files, plays Internet Radio streams, shows IMDB movie info, shows Flickr photo streams, etc. etc. it plays almost everything I throw at it!)
The advantage of this setup is clear:
1. I don't need yet another mediabox in my livingroom (saving money and energy). NAS + PS3 is all I need

2. I don't need to convert MKVs anymore (saving hours of my precious time)
I've posted a PS3MS install guide for other lucky QNAP TS-509/809 NAS owners here:
http://forum.qnap.com/viewtopic.php?p=112831#p112831
By the way, QNAP is working on a PS3MS QPKG package for the other x86 based NASes (I just beat them to it

).
Tip: PS3MS also works with the XBOX360 console.