Certificate for wifi access

I decided to upgrade to Leopard to test this out but I still cannot make it work. I click on "Get certificate" but nothing happens. There are some things I am unsure about.
1. The protocol to use. Our network administrator says the protocol should be EAP, not EAP-FAST, PEAP or LEAP which are the choices in OS X.
2. The domain to use. I guess it has to be "Login window" as this is the only domain to include a certificate but see next point
3. When using the "Login window" domain it says that it logs into the wireless network when I log into the Mac and using the same user name and password I use to log in to the Mac. The problem is that my local user name is not the same as the user name I use to log in to the network. Maybe this is the sole reason why it still fails. When I click "Get certificate" I have to submit a user name and password and then I use my network user name but it doesn't work. Is there a way to have the user names be different? If not is it safe to change my short user name on the Mac?

I was mistaken. My local user name IS the same as my network user name but the name that showed up in the log files the network admin looked at was my .MAC user name which was probably taken from the certificate that I used before (the only one I could choose when connecting in Tiger).

But clicking on "Get certificate" does nothing and when my network admin looked through the logs today he could see no entries related to me trying to connect.

How does OS X know where to get the certificate from? Can I be sure that it goes to the right source?

Sounds promising. But this requires Leopard then? I forgot to say I have Tiger on this particular Mac. But I am soon going to upgrade. So I have to wait until then?