I think if you look at session handling, that might help. What I do is use a session to stores a couple of variables (expiretime, validated, colorscheme, name, etc.) server side. The session is given a unique id, either as a cookie, or as part of the URL... 'http://www.mysite.com/mytemplate.php.SID'...
if you do this... you don't have to pass variables from page to page in hidden fields, and you also have integrity control on the things that you don't want a user to modify (i.e. expiretime, validated)
Shawn