well, if you ever upgrade to BIAB 2010, you'll have Real Band as your sequencer.
http://www.pgmusic.com/rlb_newfeatures.htm

and there's also PowerTracks
http://www.pgmusic.com/powertracks.htm

Apart from that, a relatively inexpensive sequencer is Reaper.
http://www.reaper.fm/

If you bought your M-Audio key rig new, It might have come with a sequencing program. Check your CD.

cakewalk Sonar home studio is relatively inexpensive
http://pro-audio.musiciansfriend.com/product/Cakewalk-Sonar-Home-Studio-7?sku=710003

Check the generic software rack at best buy. THere might be an inexpensive sequencing program there.