I was looking around for a free VNC server / viewer which supported multi monitors. I finally found Ultravnc but wasn't happy with the multi monitor support. When I would activate the multi monitor view I would see the second screen but only when I moved a window did I see all the other screens. Problem was the it was terrible! It was cutting off the tops of all the windows, basically it was unusable. After a little bit of research I found a fix. So for anyone who also has had this same issue here is what I did to fix it.
Go into your ultravnc installation folder and find the ultravnc.ini file.
In there change the following values to reflect the ones below
PollForeground=1
PollFullScreen=0
EnableHook=1
PollUnderCursor=1 <- Not necessary for fixing the issue but screen updates were really bad until I turned it on.
I found that on a forum.
After changing those values and terminating the client and starting it back up, the dual monitor support worked GREAT!!!.
I just thought I would post this to help anyone else out.
Enjoy!