I don't beleive this is completely impossible, just not easy, you'd need two video cards non sli/crossfire to run each monitor, vm for each video card, one would have to use a controller or something to avoid keyboard mouse conflict. I'm pretty sure it's possible, i'll be trying this and updating.
EDIT: Then again you wouldn't need to run a vm to do this if you have to non sli/crossfire cards two monitors and a controller for one user. So nevermind i won't need to test, I know you can run multiple clients of MMO games across different video cards, so this is possible without needing to use a vm.