I have been using Linux for about a year or so, and have been on Ubuntu since I started. I have recently come into a few extra machines. My main machine is a Dell Mini 9 netbook running Xubuntu 10.04. I also have an older eMachines T3990 with Ubuntu 10.10, and two low-end industrial boxes running Ubuntu Server 10.04 and openBSD 4.7.
Say I have two main machines these days, a Dell 660 with Win. 8 core i5, and Lenovo W530, also with Win. 8, and a core i7. All VM's work flawlessly on the Lenovo,
but on the Dell, I have seen issues with the same VM not working on it, as far as getting sound goes. The constant thread is GNOME based DE, which I think includes Unity.
KDE does not have this problem, but alas, I am not a KDE guy.