What Rick said! From my reading on this subject on the Net some older Win OS dont allow dual Look Up Tables(LUT) even though the card has dual monitor outputs. Good luck finding out which cards do support dual LUTs - most card manufacturers dont even mention the term - probably because they have coined their own label just to confuse us all! But Win 7 does allow this, so it may be your graphics card is the issue. Some more things to check - is your system differentiating between the two monitors? Have you set them up as extended displays - not mirrors?