There is an article about arranger software in this months issue of the dutch Personal Computer Magazine. I know most of you can't read dutch but the writer of the article made some midifiles with the different products: http://www.pcmweb.nl/pcm/item10.htm

The first midifile is made with OMB playing chords, variations and melody on the PC keyboard!

The second midifile is made with Jammer Pro using a midi keyboard controller for the melody.

The next four are made with Band in a Box. Both accompaniment and melody are generated by BIAB.

Jos