I have found a fix that allows momitsu media center 1.4 to run fine on windows 7 and 8, and I suspect vista as well.
Install the software in xp compatibility mode, and with admin permissions.
Go to C:\\Program Files (x86)\\Java\\jre7\\bin, or wherever the equivalent directory for your java install.
Copy every file (the 3 directories are not needed) to your momitsu app directory, typically C:\\Program Files (x86)\\MOMITSU MEDIA CENTER\\app
This is the directory where Momitsu.exe and Momitsu-server.exe are located.
right click and troubleshoot compatibility on Momitsu.exe, run it as administrator and in xp sp3 compatibility mode, and make sure you tell the windows troubleshooter to save the settings after it opens ok.
Watching a streaming movie from a windows 8 pc on a sony hdtv right now, looking good and streaming perfectly smoothly.
PLEASE NOTE - above directories assume a 64 bit version of windows and default install locations. Yours may vary if you have 32 bit windows or did custom installs. The duplicated java files do not get updated when you update java and that's probably a good thing. Java 7 works best so far. The duplicated java files use about 8mb of additional hdd space.