It's not only those listed Nvidia beta drivers. I have Nvidia version 182.50 released as certified on April 2 2009. There have been many drivers released since then however my Nvidia 9600 GT graphics card will not support dual monitors with any of the later drivers. When I update to a newer Nvidia driver, the 2nd monitor fails to get a signal from the card. With 182.5 all works well so I've stayed on 182.5 until I get around to replacing the graphics card.
The McAfee issue I inherited with the push out of version 10 security center was only fixed when I ran MSConfig and disabled the Nvidia driver helper on the SERVICES tab.