I also have an aging free version of mymovies setup and also run a Windows Home Server. I think mymovies is the best solution for a WHS back-end and WMC front end for sure, without a doubt. It is a pain keeping up to date however and you have to have complicated rich front ends to take advantage of it. (although with the ios clients perhaps this isn't as much of an argument) Also now its a bit costly.
As far as the DLNA part goes, It just seems like a slim down lite version of said above that works on different types of devices like your tablet, blu-ray player in the bedroom, xbox (using the video player instead of MC extender) and ps3.
WHS 2011 has a really nice built-in DLNA server with a web front end that can be used from a Silverlight based browser. It is pretty interesting to browse your home picture library or ripped CDs sitting on your home server from work in this beautiful rich Silverlight based webapp. If you use a browser not Silverlight compatible, this is not available, but you still can download the file and listen /view it off-line or in the local file system.
In the DLNA scenario there is no client end to keep up-to-date other than your normal firmware updates etc. It also supports quite a number of devices compared to the 'fat' solution with no software to install. Heck even my $50.00 Toshiba can play files off a DLNA server.
Currently I am testing WHS 2011 with the DLNA server up and running with pictures and music, PlayON DLNA server for Netflix and Hulu and WinTV with Extend to stream live TV.
The real disadvantage with the DLNA thing is displaying metadata is not consistent across players. some work some don't. Some its ok to have the metadata in the folder with the movie file, others it has to be imbedded into the file. Imbedding metadata seems to be a real pain.
So that's the summary as to where I'm at. Still very slow work in progress LOL!
Would like to solve the meta data issue with my setup so that I can start testing the movie side of things.