Have a look at "Set ANSI_PADDING" in BOL.
"Controls the way the column stores values shorter than the defined size of the column, and the way the column stores values that have trailing blanks in char, varchar, binary, and varbinary data.
This setting affects only the definition of new columns. After the column is created, Microsoft® SQL Server™ stores the values based on the setting when the column was created. Existing columns are not affected by a later change to this setting. "