Just read the following article for the (not so hopefull) view on what works and what doesn't in the audio-systems within Linux...
http://glyph.twistedmatrix.com/2009/01/dark-art-of-sound-on-linux.html
FWIW, the Mac OSX Audio system seems to be working really well and is easy to configure (e.g. MIDI routings, Audio routings etc...). Take notice and understand why OSX (and XP) are still the most popular choices for musicians on computers.