Yes, it has been a pain to set up, mainly because of my stubborness to use unconfirmed hardware (a Nvidia Quadro 600 for the Windows guest system didn't work, my Quadro 2000 now works perfect) and because of making it work on a distro that hasn't yet seen a how-to on that.
The most important step before embarking on it is to check that the hardware meets the requirements. If it does, it's quite simple.
Here some links to start with:
http://www.overclock.net/t/1205216/g...irtual-machine - good tutorial with a long thread and a wealth of information.
http://forums.linuxmint.com/viewtopic.php?f=42&t=112013 - can't judge my own tutorial, but I hope it helps. It should work likewise (or very similar) under Ubuntu. There is some more info in posts following the tutorial, to tweak stuff.