Here's a quick note in regards to my problem with Illustrator updates:

I just installed Zeph's 10.5.2 DVD and now updating Illustrator magically works! I don't know why. I've thought of a couple additional reasons, but cannot confirm them to be the solution: 1.) I removed another hard drive that had OS X Tiger and CS3 on it. Previously, this drive was connected to my system, and perhaps Illustrator update was seeing both installations and got confused? 2.) I ran Marvin's utility on the fresh CS3 installation BEFORE updating. I cannot remember if I had done this previously, but I made note of it this time, so perhaps that is the solution (instead of updating and THEN patching with Marvin's utility, which I may have done before)? If neither of these was the true solution, then there is something different about the 10.5.2 DVD from my previous manually-patched version. Either way, I am just happy that I can update Illustrator now