use WPA2 Enterprise, Protected EAP (PEAP), MSCHAPv2
you should choose /usr/share/ca-certificates/mozilla/Thawte_Primary_Root_CA.crt (screen shot from 10.10, slightly different from 10.04)
if for some reason, you can't use the security setting for CA certificate, you can ignore it, thought not recommended, you will get the warning
If you choose not to set a password for keyring, you will see the dialog box warning you about it.
go back to the network menu to disconnect