The right to sell a Macintosh together with a legally installed upgrade of MacOS X.
I think cmaier's commented on this. Also pay attention to 17 USC 117(b) on sale of installed software.
But back to what you said, copyright law allows you to install software if and only if you have the permission of the copyright holder.
No. If you've bought a copy which has been produced and initially distributed by the copyright holder (rights reserved to the copyright holder - 17 USC 106), and re-sold by anyone in accordance with the first sale doctrine (109), then installing that copy on a machine is not an infringement (117(a)).
