This must be related to something else, because trashing the windowserver.plist files will only lead to new files with default settings after a restart.
Either you have trashed/moved other files, or, an other unrelated error has happend.
If you think, you have trashed more then those plists, boot from your installation CD and reinstall the OS.
Nothing should be changed by this procedure. All missing files will be replaced.
If you are able to get into single user mode with CMD-S,
try a:
<pre>
tail -n 1000 /var/log/system.log | more
</pre>
that will print the last 1000 lines of the system-log to the terminal.
maybe you then find a reason for the problem.