post mount & IS mount ?

I have international standard disc mounts on my forks. I am looking at various forks , some of which have post mount. I have shimano lx hydros 160mm rotors. What is the difference and/or would i need different style brakes to go on these?
regard
http://www.pinkbike.com/photo/1347023/
KEEPING IT REAL RIDING STEEL
regard
http://www.pinkbike.com/photo/1347023/
KEEPING IT REAL RIDING STEEL
0
Posts
http://www.mbuk.com/forum/topic.asp?TOPIC_ID=190919
or use search! [:P]