One thing in the Fedora implementation of Samba did change somewhere during the lifespan of Fedora 7.
Up until that time, the smb service started both the smb and the nmb daemons.
Now both smb and nmb have to be started (or stopped) individually.
Take a look in:
system menu - administration - services
and see if both of those are started on your system.
In F8 as well it appears that if you open the samba service in your firewall:
system menu - administration - firewall
it is not enough to just "apply" and changes you have made, restarting the machine will have that effect of making the firewall use the new rules as it appears will "disabling" and "enabling" the firewall after changes.