Limit to the number of sockets socket_select can supervise?

Hi Im building a TCP server in PHP 5.0.2 on Windows. It will have to serve a lot of clients (500+) with low traffic. During this I have noticed that socket_select seems unable to supervise more than 64 reading connections at a time (Not good when I need 500+). It stops with a message that "Socket select failed, error code is: 10038, error message is: An operation was at tempted on something that is not a socket." These are the outputs of socket_last_error() and socket_strerror(socket_last_error()). And now forthe questions: Does any of you have the same experience? Is it something to do with Windows? Does this limitation exist on Linux? Is it just a bug? Any good suggestions? Best regards and thanx in advance HC