Here is what worked for me...
Clean install of Win 7 Ultimate 64Bit straight from MSDN. Installed Shark007's Win7 Codecs version 1.2.7 dated 8/4/2009 and then Shark007's x64 Components version 2.0.6 (website says 2.0.5 but MajorGeeks says 2.0.6). After that I installed Tversity Pro and just accepted all the defalults until it wanted to install its codec pack, I told it not to do that and then finished up. Went into the setup of TVersity and made the normal changes, Video resolution 1920 x 1080, Wired 100 Network, Optimize for Quality, Minimum Compression, had it update the libraries every hour, also make sure that you log into the Tversity service with a local account with admin rights, thats all I can remember. It was the smoothest, cleanest, easiest install / setup of a PC and Tversity I have ever had. Went into the Library setup of Tversity added my Home Server Video, Music and Photo shares and I also made one for a directory on that pc called NewMKVs and added that. Fired up my Xbox 360 and Tversity was there, went in and watched Coraline and Breakfast Club and an episode of Philanthropist, they were are pristine, didnt matter if it was coming from the driectory on my pc or from the homeserver, results were the same. I had no buffering or stutters, it just worked, frankly I could not believe it.