There are benefits to 10.5.7. The most important one to me is it fixes a bug in Apple’s Mail program— a bug that gradually slows your Mac way, way down when Mail is left running for a long time. I have not seen any new or different features in 10.5.7 and Apple is not advertising any, so maybe it really is all bug fixes. Anyhow, I’m glad I did the update.
If you want to apply the update on your own be sure that your machine is in good shape before you apply the update. Restart your machine, quit any programs that launched as startup, then run Disk Utility and repair permissions. If you have problems with Disk Utility it would not be wise to do the 10.5.7 update. If you don’t have trouble, go ahead and update.
The best way to do the update is to get the so-called “Combo” update. It’s bigger than the update that comes when you do Software Update under the Apple Menu, which means it takes longer to download and install, but I’d use the Combo update anyway. Applying a Combo update will reinstall system pieces that have somehow gotten lost, in addition to updating the machine to 10.5.7, and generally speaking the Combo update is the way to go. Takes a little longer, but worth it.
Here’s the link to the 10.5.7 Combo update. Remember to quit all of your programs before you do the installation.
Call me if you’re stuck– preferably, before you’re stuck.