Kindle Cloud Reader Probably the easiest and most effective solution is to read your second book in Safari by way of the Kindle Cloud Reader. Go to read.amazon.com and get set up in moments with a few simple steps.

The latest version of Kindle for Mac requires Snow Leopard OS X 10.6+ but you and there is no longer a download available for Kindle 1.5 for Mac which works on OS X 10.5.8 Leopard. If you can find one however, you must uncheck Automatic Updates in Preferences in order for it to continue working on your Mac. Just go to Preferences, select the Updates tab and uncheck the checkbox. If you don’t do this, Kindle for Mac will automatically update to the latest version which doesn’t work on Leopard.
Alternatively, a better way to go is to use Kindle on OS X 10.5.8 is to use Kindle Cloud Reader which is Amazon’s online version of Kindle:

Nook Reader For Mac Book Pro

Download Kindle For Macbook Air

This doesn’t require downloading anything and you can access it anywhere you have an internet connection no matter what version of OS X you are using. If you have any problems using the Kindle app on OS X 10.5.8, let us know in the comments below.