Hiya Amitrus
If you have a page A containing a frameset with pages B and C (B being the PHP-script) you'll have to make page A into a PHP-script too.
That way when you open page A (containing some variables in the URL), you can create your frameset WITH whatever variables you want to transfer.
If on the other hand you are not able to change the way page A is made (eg. you cant change it to a PHP-script, I suggest you use JavaScript - read the querystring from page A, get the variables you need for page B and then use "location.href" for page B. It can be done using JavaScript but isn't as neat, fast and flexible as using PHP.
Contact me if you'd like to get som code.