I'm unaware of anything that will connect Windows Media Center to Android devices.
I made the switch from WMC to Plex a year or so ago specifically so I could use the same media library on multiple TVs and devices with a somewhat standard interface (2 adults and 4 kids in the house), the Plex Media Server will serve up media to Android and iOs devices, Rokus, and Windows and Mac machines (and in a more limited way to DLNA-compliant devices like Western Digital media players and a multitude of network-enabled Bluray players and TVs). It requires you to keep the computer with the media server running of course whenever you want to watch media on any of the devices, but it works quite well (transcodes the media on the fly based on the capability of the device it's streaming to) and has a pretty simple interface, and is pretty simple to set up.
Depending on how your WMC video library is organized, you will probably have to go through and rename everything (as 'Movie Name (year)" from The Movie Database) but with that Plex will scrape your media and do a near-flawless job of pulling down fresh metadata. Plex is also very good with TV shows (create a folder named "TV Show" and put the episodes in that folder named "TV Show - SnnEmm" where nn is the season number and mm is the episode number).
Of the available Android set top boxes, I've waffled over buying a Sony NSZ-GS7, it seems to get the best reviews and comes with the Plex app pre-installed, but I don't have any personal experience.