Yes, in your initial post, you can do it via a form or using the curl function. If you don't have curl support in PHP, download and install the binary and use exec() or system() to call it. curl is fast, easy to use, and gets the job done.
Then in your PHP, to POST again, use curl to post the vars.
Of course you can do it the hard way by writing your own POST function by initiating a socket to the HTTP server, passing in the headers, passing in the POST data, getting the output and closing the socket... but you might as well use curl and simplify it :-)
A good place to start is to look thru the manual for the curl functions. But if you don't have the curl extension, just install the binary on your system and refer to the curl documentation to find out how to POST data to an HTTP server.
i don't know the homepage for curl, but just type it in a search engine (or goto freshmeat.net and type it in the search).
-sridhar
P.S. hmm... i seem to be fond of curl... probably because I use it with Verisign PayFlow LINK to POST data to their server for CCard processing and I don't even have to upgrade to their expensive PRO version :-)
