If you're doing it in 'C', then a delay loop is not a good idea. This is because 'C' does not guarantee that any given source line will generate any particular set of machine instructions.

If you want to use delay loops to generate specific time intervals (and I don't think that would be a good idea for 1s), then you must use assembler.

http://www.8052.com/forum/read.phtml?id=42841