Running a program whilst Mac idle

Hi I’m very new to Automator let alone Applescript. I’ve do scripting for Flash apps but that’s it. I’m a little confused with trying to get my torrent software opened up when my iMac is idle, but then shut down when it isn’t. I seem to leave the Mac on idly when it could be downloading whilst I’m not there on it. Is that possible?

Thanks.

I’ll endeavour to help out in the forum as much as I can; my expertise permitting.

Model: iMac
Browser: Safari 525.20.1
Operating System: Mac OS X (10.5)