[izz]

lol
thanks for your prompt response and manner.
But I feel that your didn't get my suggested solution well.

I meant two databases but one single (user) table.
For example we may setup the english forum normally, but in the Arabic version we modify the register.php file so that it submits the registrations to the English database/user table.
Whenever a user changes his password, the change will go to one table which is used by both versions.
The hack should care that any user related action shall deel with the english database.

This is just to clarify my idea. But still I guess your solution is easier but I may need more hints on deeling with styles, and how to let the "unregistered" viewers see the desired language.
In all cases I appreciate your manner and logic Mr. Logician