I have the same problem on my Asus 1000, What you have to do is hold down ALT key and lock your mouse with left key and move window.
while this is handy when on the desktop i can't remember if this is possible during install?
not just during install, but also using VNC - holding Alt key drags the whole vncviewer window, activating remote Alt via vncviewer menu and then trying to drag any window inside does not work ...
(however, the workaround in that case is to start the vncserver with larger screen size and use the sliders provided by vncviewer, but it is extremely uncomfortable in case all your work can be done in a smaller size but only one window does not fit, and because of this one window you have the bigger size and you have to be draging the sliders all the time ...)
K.