Do make a backup of the current setup!! That may come in handy.
> and until now even the mouse wheel isn't working. The same
> I'll try to keep Ubuntu, as my distro, just for emergency cases I'm
All of your preferences will be met by debian. Pulseaudio is optional
and the debian-multimedia team are on the forefront when it comes to
pro-audio packages.
Also note that OpenDAW (64studio's successor in the making) is based on
debian/squeeze.
Other alternatives matching [most of] your criteria would be Arch and
maybe gentoo.
BTW vanilla 2.6.39 includes the relevant RT patches for pro-audio,
although there is no official package, yet. Meanwhile the OpenDAW kernel
does work on 64bit debian systems: http://apt.64studio.com/backports/pool/main/l/linux-2.6/
Anyway, choosing a distro for *Desktop use* is quite a personal thingy
and a matter of taste. Give it at least a week after install, else you
can't tell if it sucks or if it is just different from what you are used
to (and that includes Ubunutu).