Check if SQL Server version is 2005 or lower

if SERVERPROPERTY ('BuildClrVersion') is null
begin
    -- some 2000 specific code
  print '2000'
end
else
begin
    -- some 2005 specific code
  print '2005'
end



----------------------------------------------------------
--
-- practical example:
--

-- to allow xp_cmdshell execution which is disabled by default on SQL 2005 but not on 2000
if SERVERPROPERTY ('BuildClrVersion') is not null
begin
  -- To allow advanced options to be changed.
  EXEC sp_configure 'show advanced options', 1

  -- To update the currently configured value for advanced options.
  RECONFIGURE

  -- To enable the feature.
  EXEC sp_configure 'xp_cmdshell', 1

  -- To update the currently configured value for this feature.
  RECONFIGURE
end