restrict login on multiple domain network to single domain

Hello,
I want to limit user logins. Currently when you are at the login screen the user has the ability to select multiple domains (1 of 5 domains) on our network. I want to enforce a domain wide group policy that restricts it so that only users of a particular domain (C_DOMAIN) have access to its domain PCs (workstation@c-doamin). Our DC are running Windows 2003 Server and all of our workstations are running Windows XP Pro.
Example:

login drop down menu shows
A_DOMAIN
B_DOMAIN
C_DOMAIN
D_DOMAIN
E_DOAMIN
I want it so only user@CDOMAIN has the ability to login to C_DOMAIN PC