alternativly put the check part at the top of the script.
Remember, you can have a form with variables in after you check the variables...
//top script
if ($something == $somethingelse) {
//show members area
}
else {exit;}
//bottom script
//form stuff
(NB: I'm currently having problems with my else statements objecting to me, so if the above gives an error...)
The theory is okay though