There was some discussions on what distro to use. FWIW I am using a
jaunty build of ubuntustudio, but not with the standard RT kernel, which
has some awful bugs in it. Instead I am using a custom real-time build
of 2.6.29.5 (2.6.29.5-rt21-all-nvk-062109-1) provided by "Realtime
Dutchman". Information on this kernel can be found in this bug report:
https://bugs.launchpad.net/ubuntu/+source/linux-rt/+bug/290498. It seems
to work well, laying the awful Intrepid nightmare kernel problems
finally to rest.
I have read some good reports about ubuntustudio Karmic, but having a
combination that works well, I'm loath to risk upgrading just now. I
build my own Jack, Rosegarden, Zyn and Yoshimi from source (stable for
jack, beta for RG, latest GIT for Zyn, latest dl for Yoshi).