Linked server

-- get exists linked servers:

select * from sys.servers

-- add new linked server:

exec sp_addlinkedserver 

@server='Dev2008ItaiTest', -- the name of the linked server

@srvproduct= '', -- the product name of the OLE DB data source

@provider='SQLNCLI', -- the unique programmatic identifier (PROGID) of the OLE DB provider that corresponds to this data source

@datasrc='DEV2008', -- server name

@location='', -- the location of the database as interpreted by the OLE DB provider

@provstr='Query Timeout=10' -- another parameters.

Notes:

• If the product name of the linked server is SQL Server, provider_name, data_source, location, provider_string, and catalog do not have to be specified.
• Return Values: 0 for success or 1 for failure.

-- use linked server:

select * from Dev2008ItaiTest.DBName.dbo.ObjectName

-- delete linked server:

sp_dropserver @server='Dev2008ItaiTest'

http://msdn.microsoft.com/en-us/library/ms190479.aspx