Well, I downloaded Mobireader for PC, found my PID, bought the .prc for $6.14, found mobidedrm, learned to navigate DOS, installed Python, through considerable trial and error got mobidedrm to work aaaaaaaand...Unsupported Compression Method in FBReader
I guess I'll attempt a format shift in Calibre and see if anything intelligible comes out the other side. Fourth or fifth piece of software's the charm, right? I can't see using the Mobireader software--it's a bad iTunes knock-off for books, making very poor use of my display area.
Don't mistake my tone--my frustration is not with you guys, who are pointing me in the right directions, but with the lack of vision in this industry and the resultant babel of hacks, work-arounds and redundancies. While I can understand the chain of events that has left ebooks--text!--so far behind other electronic media, the situation is nonetheless shocking and absurd.