ill let you know the outcome of my testing here are some of the distros im testing on a dual core intel 2ghz pc with 3 gig of ram.
AVlinux – Debian based OS – recent versions – lxde desktop
KXStudio – Ubuntu Based – KDE desktop – recent versions
Ubuntu Studio – unity – recent versions
Studio64 – debian based – seems obsolete
It seems there are more but these seem mainstream, the kxstudio seems pretty good for newbies with the cadence app, Im looking at probably setting up a ubuntu studio with the kxstudio repositories so i can install cadaence and carla apps, but probably do some testing with kxstudio first … i just dont like KDE so might just put a lxde desktop or unity ontop of kxstudio …..
Ive also seen write ups of people installing from the ground up a cut down version of ubuntu with the realtime kernel which sounds like a good idea…