Morrowind and Oblivion are both awesome games. I would put Morrowind ahead of Oblivion in terms of the uniqueness of the story and feel of the world, but Oblivion has better graphics and less buggy gameplay (discounting mods applied).
Cliff racers still creep me out, though, no matter how many times I played Morrowind. If you get any mod/fix, make sure it's one to limit the spawning or aggressiveness of Cliff Racers. It's been a while since I played either game, so I don't remember mods offhand, but make sure you get all the high res texture files if your system can handle them.
The games are definitely a steal at those prices. I'm going to buy them now to add to my small collection of Steam games. I would even purchase those games for the music alone (Jeremy Soule is an excellent composer, and both soundtracks have an "epic" feel) at those prices, if I didn't already own the soundtracks.