PHP now comes default with the register global values off by default now. Look in your php.ini file for register_global and set it to yes, true, or whatever the "On" option is.
instead of $posted_variable, it is $_POST['posted_variable'] (Omit the apostrophes if echoing inside quotes). Any future code development you do should be using this new method by default. It is more secure and faster.
Hope that helps. Pulled my own hair out for hours after upgrading.
Ron