Hi all, in my board i have a trouble.

I have some nicknames like this http://utenti.fuoriditesta.it/the-ida-iamma-8-173626/ or this http://utenti.fuoriditesta.it/ssibid...dhi-bu-187669/ that gives me some troubles with mod rewrite.
I want to disallow unicode in nicknames but still allow all european characters and keyboard symbols (like |!"£$%&/()[]{}~=?^'ìè+ùàò,.-é*§°ç;:_@#<>€ and spaces too).

What regular expression i need to use?