domain name change -- coonection denied

If you use Windows authentication for database access and they chnage the
name of the Domain is there anything other than creating the news groups
that needs done to allow access?

Example:

domaina\Itgroup


New

domainb\itgroupb.


I tried to create the new group under that domain and give the same
permissionsas the old definition but when one of my developers using
SqlExpress to to connect(Windows authentication) i says not a trusted sql
connection.

I then used xp_logininfo 'domaima\itgroup',members.

I can see he is defined within he group but the only thing that looks new
is the path. The other pieces of the display still show the old domain name.

Any thoughts or suggestions?

Thanks