I have dual monitors and haven't been able to do it, myself. I don't know if it's possible to run 2 seperate desktops/windowblinds at the same time off of the same video card.
Nvidia lets me run 2 seperate wallpapers and that's about it. I have never used it, but UltraMon gets some pretty good reviews for being able to do some things that some or most video cards can't with dual monitors.