For personal stuff I have an HP Vision APU based laptop, it is running Fedora - It took two full days to get it there due to issues with the video driver support. I know, it is a newer system so I have to wait for enough reverse engineering or open source drivers for it to work well...yep.
For work, I use Windows XP still - Only because I have to!
For my second job I use Mac OS X (early 2011 macbook pro). I have had plenty of problems with it, battery problems after upgrading to Lion, running Virtual Machines on it makes it so hot that I nearly need a set of tongs to handle it. I run Ubuntu and Windows 7 on it in virtualized...
I really would like to move to either Fedora or Ubuntu on all my systems, but I can't due to some tools and systems I access. SSL VPN won't work with OS X because the TUN adapter needs root to install, unstable video on Linux (at least on my new laptop) and incompatibilities between Libre Office and MS Office. I will just keep using them all for the tasks that they work for until something happens to make things more even across the board.