if i remeber correctlly ffmpeg worked with wmv v1-2 (aka the 'old stuff') and just recentlly added support for wmv3 which is what most moives are distributed as nowdays and is the one wthat works with DRM if you enable it.
i guess you figured out that if its DRM'd then you cant use the spiffy new wmv v3 support in ffmpeg.
encodingmplayer by hand is great and easy to do, i do it for every major distro i use rather than stick with what the distro supplies. the only thing you should need are the alsa headers (unless you use a 2.4 kernel) and the fbdev kernels for the command line (ie no X/qutopia) if you want X and qutopia then grab X11-dev and Xv-dev as well as the qutopia headers (i assume the are qt-dev)
make sure you grab the svn version and do it with svn co <addr> as it will also grab the latest ffmpeg as well