I now have Xubuntu 12.04 on three of my machines (two HP laptops and a Dell Dimension 3000 desktop). Love it! Works very well.
I don't spend much time on my iMac anymore because I have really lost interest since Lion was releaed a while back. The more I use Linux the harder I find it to go back to my iMac. At the moment I have a partition set up on my iMac to install Xubuntu 12.04.
PulseAudio has been in use in several Linux distros as the new standard in managing sound. But in some systems - probably older ones like mine - it's a complete failure. Thanksfully Xubuntu did not ship with PulseAudio like the other members of the Ubuntu family did, until version 10.04 (Lucid Lynx). Rawr. It wrecks the sound on my old Dell Dimension!
When I first installed Xubuntu, everything was working fine. Then I encountered a problem where it would start up in the command line with no GUI, but I fixed that by typing startx. The problem, though, is that whenever I start it up from the command line, the sound is muted. I am using version 12.04 on a Dell Dimension 3000.