I’m in the midst of creating different volumes (or partitions if you will) to maintain specific versions of Mac OS X, Final Cut Pro, and Avid Media Composer. Part of the process is following the compatibility version matrix for Media Composer.
In my situation, the matrix suggests 10.5.5 and QuickTime 7.5.5 for my copy of Media Composer 3.13. Starting with a clean installation of 10.5.0, I remembered there are Delta and Combo updates for each revision. Curious to know more I found this page at The X Lab.
The author provides some background on the update process and a list to Apple Support for notes and downloads of each Mac OS X revision. Although Snow Leopard is missing you can find every “point” update from 10.2 through 10.5.