usernames with special characters

[Danda, Richard SFC]

Is it possible to set up Red Hat Enterprise Server 4 to allow for user names
like:  firstname.lastname; I have gotten the Enterprise Server winbind/samba
to enumerate users on from a Windows Server 2003 machine in VMWare, but I
can only log into the linux boxes with user accounts that are alpha/numeric.
Any ideas. 
 
Thanks,
 
Richard