crontab support for PHP

Hello everyone! I'm new to this list, therefore I do not know if you have discussed this matter before. I'm interested in something like crontab for PHP. This should be plattform independent and easy to maintain. I have a few ideas of how to implement it even though I'm rather new to PHP. I'm do not have much experience of crontab but I have the need for something like it on Windows. Also, if you have PHP compiled as a module there is, in my opinion, no good way of schedule running of scripts. What are your thoughts on the matter? /Max