declare @sql varchar(8000)
select @sql=isnull(@sql+char(10),'')+'exec sp_rename ''['+a.name+'].['+b.name+']'', ''['+substring(b.name,4,128)+']''' from sysobjects a join syscolumns b on a.id=b.id where a.type='U' and b.name like 'xx[_]%'
print @sql
exec (@sql)