Excel Help - Macros question?

So I have a file with about 18,000 rows. I have to god help me – divide this file into different files separating the file in groups of 100. So I take 100 rows past it into a new sheet and save….then over and over and over til I run out of lines. This is painful….and slow. I know there is a quicker way to do it with macros but I don’t have much experience with them. I tried to record one but it kinda pasted the first 100 and stopped. Can anyone write one for me or tell me a quick suggestion. Im at work now lol