Leopard

Hi, dogger, and welcome to Apple Discussions. No, the OS installer discs that come with your iMac will be specific to that model and won't work on another model. In addition, the software on them will be licensed for use only on one computer at a time, so installing it on two Macs at the same time would violate the license, if you could do it. But if you buy a retail Leopard installer for your MacBook, you can run Leopard legally on both your computers.

Yes.

If you purchased your MacBook on or after October 1st you are eligible for the update program.

Mac OS X Leopard Up-to-Date Program

I don't think you can run the SAME copy legally on more than one Mac. That is why they're selling a "family pack" of 5 licenses for $199.

http://blogs.pcworld.com/staffblog/archives/005700.html

The Big Cat will be available worldwide on October 26. The Ultimate version will cost $129. As we've already noted on this blog, a multi-license version will be available as well, intended for households with up to five users: This family pack version of Leopard will cost $199--worth pointing out for its value to multi-computer households, as compared with a comparable upgrade from Microsoft Windows XP to Vista.

Apple announced the min system requirements for Leopard (10.5) as:

* Mac computer with an Intel, PowerPC G5, or PowerPC G4 (867MHz or faster) processor
* 512MB of memory
* DVD drive for installation
* 9GB of available disk space