It looks like I have the dreaded windows server problem

I managed to get the calendar to appear by changing line 38 of ajax-common.inc.php from ac-includes/ajax to ac-includes\ajax.
But when I try to log in to admin I am getting the error message ac-config.inc.php not found. I have tried every possible combination of forward and backslashes in ac-admin\index.php to define the constant AC_ROOT but cannot figure it out, I followed the thread that has the fix but nothing seems to work, can you help?
Thanks, Anthony