Twice I have installed Linux, and chosen "Use Graphical Login" and both times that hasn't worked. Running Xconfigurator fixes the problem.
There is a known bug that if you select to have X start on boot, and then choose to customize the X configuration, then the first setting is lost and therefore you do not get the graphical login. This problem is fixed when using the latest boot disks and updates image, but that is probably a lot more trouble than it is worth considering that you already have the system installed and have come up with a workaround to the problem. Thanks for the report.