and...i believe that the only way you can use the task scheduler on win is if you have the cgi version of apache, not the apache module, since you can't just run a php page or something like that, you would need to call a command via command line with the task scheduler
and yes you can use cron on nix, with either wget or lynx to run a php page, simply use google to search run php page with cron and you will see many tuts out there