I may have posted here before; then again, my answers are probably different now.
I have a Mac and I recently upgraded from Snow Leopard to Mountain Lion (I skipped Lion). Mountain Lion has broken a few things. The one that has affected me is Mono Framework. On the other hand, Time Machine can now backup to more than one hard drive. Yea!
I also use VirtualBox when I need to run a different OS:
I use VirtualBox to run Ubuntu 10.04 LTS. Support for 10.04 is about to expire (April 2013), so I have an installation of 12.04 LTS as well (LTS stands for Long Term Support). Traipse is not compatible with the default Python version in 12.04. That's why I continue to use 10.04. eh....
I also use VirtualBox to run Windows XP. I tried Vista, Windows 7, and the Windows 8 Preview. XP works best for me.
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EDIT: I was surfing backwards, and bumped into my previous post.
QUOTE(jayzee @ Jan 1 2011, 23:46)

... I run CentOS as the host OS. I run Windows 2K, Windows XP, and Ubuntu as VirtualBox guest OSes....
I found it interesting that nobody had anything to say about it. I wonder if anyone will have anything to say about this one.
This post has been edited by jayzee: Dec 25 2012, 20:44