Find out when not interacting with my mac

HI,

i want to find out with cocoa when i'm not interacting with my mac.

example:

if i dont move the mouse and dont type on the keyboard for 5minutes or so, i want to call a specific function with shows a popup or something.

how can i do this?

thanks in advance,

flo

System Preferences - Desktop and Screensaver- Screensaver tab- set it to 5 minutes - ;D