Come Fedora 10 and the Root login at the default GNOME Welcome screen is disabled. So, if you say try to login as user root, you won`t be allowed to login. So, here`s the work-around.
1) Setup SUDO
2) Setup Root Account:
[user@localhost ~]$ su
[root@localhost user]# passwd
Changing password for user root.
New UNIX password:
BAD PASSWORD: it does not contain enough DIFFERENT characters
Retype new UNIX password:
passwd: all authentication tokens updated successfully.
3) Open the file named gdm located in /etc/pam.d folder. You need ROOT privileges to edit this file. Now locate a line which reads as "auth required pam_succeed_if.so user != root quiet" in the file. Comment out this line by adding a # to the beginning of it. Then save the file. You`re Done!