multiple forums one login

Hi, this must be a simple concept so I hope someone can assist with this.

I arrange to make all users registered in multiple forums have their own user id and password on each of the forums on my website.

I want to put a drop down button on each forum page in the header so they can  select to jump to one of the other forums and pass their user id and login info to the new forum page so that the second forum sees that they are registered and the user does not need to log into all three forums.

Is this possible? Will there be aproblem with session variables etc or will this work if I have the corect url to pass the two variables values?

If this would work can any write the line of code for me pelase?

ok thanks brog.

As I understand what you have said on these posts it is not advisable to run the 4 forums from an acces database and it is not going to be easy to code for the above idea. That means I must wait until I migrate to ms sql databse so until then the ygotta log in separetly. Thats the way its gotta be