Conditionally show a column

I am creating a registration form for events.  Each event has a number of open seats.  I have used workflows to successfully handle the number of available seats, but I now need to include a conditional column in that event that will be a link to the registration form (which is a separate SharePoint list).  This link would show if available seats is greater than zero (0), but will display "Closed" if it does reach zero.

Is there a way to do this, and secondarily, how can I link to that list and display the text "Register"

Thanks

Brad Allison