Are there any good frontend programs for MPC?

The very best one is Speek's "MPC batch encoder"

Check it at:
http://home.wanadoo.nl/~w.speek/batch_encoder.htm

Or you could try Musedrop. It's a drag'n'drop frontend. All you have to do is choose a quality setting, and drag a .wav file to the program's window.
http://www.inf.ufpr.br/~rja00/
Near the bottom of the page.

Regards;

Roberto.

Many thanks!