sqlserver exchange instance name

0
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I followed the procedure mentioned in http://sqldbpool.com/2008/09/03/how-to-change-sql-server-instance-name/like this
For default instance

sp_dropserver 'old_name'
go
sp_addserver 'new_name','local'
go

For named instance

sp_dropserver 'Server Name\old_Instance_name'
go
sp_addserver 'ServerName\New Instance Name','local'
go

 
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I installed VS2010 and it automatically installed SQL Server 2008 Express.
Now, the installed instance is called SQLEXPRESS, therefore to connect to it I have to use 'localhost\SQLEXPRESS' or '.\SQLEXPRESS' or something like that.
I want to rename the instance so I can connect using only my computer name or 'localhost'.
How do I do this?
 
I'm not sure of the express version of SQL Server bundled with VS 2010, but with the Standalone SQL Express 2008 (or R2), running the setup again will let you create a new instance.