Hi Shark,
first, you can follow the KB article 918992 to transfer
logins and passwords.
after this, you can refer to this article:
How to: Rename a Computer that Hosts a Stand-Alone Instance of SQL
Server 2008/2005
http://msdn.microsoft.com/en-us/library/ms143799.aspx
[font="Verdana"]CU
tosc[/font]