I also liked Media Portal. After I got my HD tuner card I tried out everything but SageTV. For my specific card the Windows drivers were horrible, so I ended up with MythTV. But for "out of the box", I liked Media Portal the best. Easy setup, and some really cool features built in. For example it automatically retrieves video art & info from IMDB for your DVD's out of the box with no configuration.

If my tuner card worked better with Windows, Media Portal is what I would be using. (And in addition to watching/recording multiple things from one tuner, it does now support a client/server model.)