I am using the latest daily build of Ubuntu 12.04 on an machine with Asus P5G41T-M motherboard using the built-in graphics (GMA X4500). I have not installed any additional software such as compiz, etc.
I have enabled the default VNC server through the "Desktop Sharing" dialog in settings. When I connect from a Windows 7 machine using RealVNC or TightVNC, the screen doesn't refresh correctly. There are old images left, the new windows do not appear entirely.
I have tried setting disable_xdamage = true in gconf-editor as others recommended for 11.04 and 11.10 but it didn't help.