5
First can you send a copy of your .htaccess file?
And second, if you do your redirect like this the users id will be passed correctly.
RewriteEngine On
RewriteRule ^([0-9]+)$ your/desired/path/file.php?userid=$1 [R]
The [R] flag tels apache to redirect. And if you want to keep it real nice you could replace [R] with [L]. If you do this the user won't be redirected but just stays on the current url, while the desired file is still loaded.
Greets Dylian.
BTW To get the users id from within the template you could then use <{$smarty.get.userid}>