A way to check if foreign key exists in SQL 2005

You can use this script:

IF EXISTS (SELECT * 
           FROM sys.foreign_keys 
           WHERE object_id = OBJECT_ID(N'[dbo].[FK_NAME]') 
             AND parent_object_id = OBJECT_ID(N'[dbo].[MyTable]'))
BEGIN
    -- do stuff
END

This can be done if you expand out the table and right click on an existing FK and choose script key as "DROP TO" and then you will get a generated script from SQL.