newbie question regarding domain name in login

[Hussain Ali]

hi,

when windows clients connect to my unix box
they can not just use thier login names, they have to 
type "domain-name\login-name" instead of just "login-name".

is thier a way to set this domain name , without users having 
to actually type it?

note: everything else seems to work fine. 

-hussain

"Understanding is a 3 edeged sword, your way, thier way and the Truth"